Has happiness ever been so deeply troubling? Barely a week goes by without some poll telling us how miserable our children are (Unicef), or how Britain has been ranked 41st on the world map of life satisfaction (University of Leicester). Why can't we be like the sunny people of Denmark (No1) - or even Bahrain, straight in at number 33 with its fancy oil refinery and votes for women? What's our problem? Look at us - we're prosperous, handsome and fit, with a TV in every bedroom and a chicken in every fridge. And yet a survey carried out for the BBC last year found that only 36 per cent of us would describe ourselves as 'very happy', compared to 52 per cent in 1957 - yes, those well-loved, carefree days of bread and dripping, toothache and Arthur Askey.

British happiness levels have been static since the Seventies, which mirrors the experience of most developed countries. Economists say that when average incomes reach about £10,000, life satisfaction starts flatlining. In other words, money can buy you happiness, but not for long. Once you have everything you need (food, shelter, matches) your mind gets sucked into a spiral of unquenchable wants - patio furniture, profiteroles, vodka, broadband porn, ranch-style housing, luxury travel, breast implants, nicer shoes. We are never satisfied. It doesn't help, when we gaze out from our mountain of personal debt - British households were in hock for £1.3 trillion at the last count - that there's always someone waving at us from somewhere just a bit higher up the hill. It doesn't help either that our work-life balance is poor and that we are anxious about the decline in public manners, or the growing difficulty of getting from A to B. Men are contemplating their falling sperm counts; women are forgetting to have babies. God we're miserable.

I'm not feeling too ecstatic myself. I am stuck in traffic on the M25. I'm heading for a 'wellbeing' conference at Wellington College, an £8,000-a-term public school in Berkshire. At the end of last year the school's new 'superhead', the historian and political biographer Anthony Seldon, introduced 'happiness' lessons for its 14- and 15-year-olds. Now he wants to spread the revolution to other schools.

Can happiness be taught? Previous orthodoxy had it that happiness was determined by genes and upbringing - studies with lottery winners and paraplegics suggested that a misanthrope who becomes an overnight millionaire will sink to his 'natural' level of misery once he gets used to the money, just as a natural optimist will readjust more readily to losing the use of his legs. But in the past five years positive psychology has been mushrooming across US academic institutions (it is Harvard's largest course). It's fuelled by Martin Seligman, a professor at the University of Pennsylvania and America's most influential psychologist, whose studies have led to a radical switch of emphasis in research and therapy from the postwar practice of looking at damaged lives to looking at ones that work. 'The focus on pathology,' he wrote in 2000, 'results in a model of the human being lacking the positive features which make life worth living. Hope, wisdom, creativity, future mindedness, courage, spirituality, responsibility and perseverance are either ignored or explained as transformations of more authentic negative impulses.'

Positive psychology isn't an entirely new idea. The late Thirties saw a blossoming of research in giftedness, marital happiness, effective parenting. But war supervened, and its freight of homecoming trauma victims determined the path that therapy would take, where 'thousands of psychologists found they could make a living treating mental illness'. Seligman says there's not much left to learn about malfunctioning minds. Happiness is the future. Using placebo-controlled mental exercises on volunteers and programmes for clinical practitioners, he proved that individuals can substantially raise their base satisfaction levels. His activities for patients with depression were measurably better than drugs. Anyone could be happy.

You don't have to be depressed to want more life satisfaction. Last year the BBC screened The Happiness Formula (to which Seligman contributed) and Making Slough Happy. The latter encouraged 50 citizens to improve their wellbeing with 10 simple tips 'culled from global happiness research', ranging from counting your blessings to smiling at strangers. I don't know if it succeeded. It doesn't seem to stretch one's negative thoughts too far to imagine it didn't. And yet you can see why they might want to try.

Slough isn't a million miles from Wellington College, though it is if you go the wrong way up the M3 as I do. Unsurprisingly I am running dangerously low on wellbeing when I finally turn into its topiaried grounds. The conference is well attended. Anthony Seldon, a diminutive, magnetic figure, makes a speech lamenting the 'utterly terrible' way we crunch our children through the exam system. Schools should be harmonious and inspiring, he says. He talks about the important new science of wellbeing, and anticipates naysayers and cynics with a list of pithy rebuttals. He is serious but also deadpan funny and gets a laugh when he uses the word 'bollocks'. He leads the 200-plus crowd of teachers in a few minutes of meditation. I already wish he'd been my headmaster.

The wellbeing course they teach is drawn from research carried out by Dr Nick Baylis, Britain's first lecturer in positive psychology at Cambridge and co-director of the university's Wellbeing Institute. Baylis explains how, through his study of 'healthy and good-hearted lives' (he punctuates his address with rousing quotes from alpha achievers Steve Redgrave and SAS commander Peter de la Billiere), he has formulated skills that can be learnt.

He talks about 'channelling negative emotions' and the importance of 'healthy and creative partnerships'. These - along with a good night's sleep, exercise and decent nutrition - are the tools to help a young person conquer their fears, reach their goals, to be whole. He tells us about the stammer he had as a kid. How he retreated from his early life by watching 14,000 hours of TV. His academic achievements include the lowest-ever recorded grade for a degree at Exeter University. In his tall, tousled, self-joshing, plain-speaking fashion, he is a Manichean James Stewart, taking a stand for honour and truth and beauty and goodness.

It's not difficult to see how this inquiry into happiness - the citing of sporting and showbiz exemplars who have fought the odds and lived the dream, the feelgood language of the self-help bestseller and life-coach - might invite comparison with the folksy nostrums of popular culture, not to say jeering headlines. But everyone says the science is hard as nails. And what if it works? Who can be against feeling good when the alternative is feeling bad? No one here, though at one point Toby Young (author of How to Lose Friends and Alienate People) stands up to denounce the proceedings as 'facile' and to demand where the world's great artists and writers would be without a little unhappiness. Seldon suggests that it would be unfair to deprive children of a well-adjusted life on the off-chance that one of them might turn out to be the next Dostoevsky.

After coffee we hear from Richard Layard, a Labour peer, emeritus economics professor at the LSE and author of Happiness: Lessons From A New Science, who reflects disapprovingly upon the 'tsunami of individualism' in Britain and America that has followed the collapse of religion and socialism. 'Schools have to be in the vanguard of the new civilisation,' he says, praising the advances made by positive psychology in the US, where the 'evidence-based policies' of Seligman's 'resilience programme' have seen reductions in antisocial behaviour and depression. Layard is behind a project to roll out the scheme for 11- to 13-year-olds in Manchester, Hertforshire and South Tyneside.

Before lunch, the school's head of PSHE (Personal, Social and Health Education) Ian Morris, who tailored the course for Wellington with Baylis, demonstrates the links between our biology and our emotions, and directs a 'classroom' role-play exercise in which a young woman 'channels' her anger into something calm and reasonable. It's not entirely convincing, though I suppose it could be fun for teenagers.

It's hard to get more than a taste of what the course offers. I flip through the handbook, which runs deep and wide with topics from sleep and diet to bomb disposal, to what 10 years of crystal meth can do to your face. I learn from a study into saliva carried out by the Goethe University in Frankfurt that singing stimulates the immune system and improves mood. I discover (via researchers at Harvard) that people who think everything is funny live longer. I immediately think about my mother, who could laugh for Yorkshire and who is now 131. I vow to laugh more, but what at?

Later, back on the spirit-draining, gridlocked reaches of the M25, I find myself remembering that it's not just kids who need to live well, but adults, too. According to the BBC poll, 81 per cent of us think the government should concentrate on making us happy rather than well off. The issue has been a 'wake-up call' for politicians. David Cameron told the BBC last year: 'We should be thinking not just what is good for putting money in people's pockets but what is good for putting joy in people's hearts.' Even in 1999 Tony Blair acknowledged: 'Money isn't everything... Delivering the best possible quality of life means more than concentrating solely on economic growth.' Since then, there has been a rising clamour for more happiness, or less unhappiness, most recently with Oliver James's book Affluenza, which identifies mass consumerism as the root of our malaise. But if cars and holidays and celebrity culture can't satisfy us, what can? The procurement of wealth - as measured by GDP per capita - has been the default measurement of policy-making for so long it seems inconceivable it could be supplanted by anything so slippery as happiness.

Wheels of government are beginning to turn on the issue. Two dense reports carried out by Sheffield University for Defra last year looked at international research into the factors affecting wellbeing, and ways in which they might influence sustainable development policies across departments. Some of the findings are less than overwhelming. I wasn't surprised to learn, for example, that 'people higher in self-esteem seem less likely to suffer depression'.

But there were subtler things. Being separated is worse than being widowed. Raising children, far from being an unalloyed joy, is 'an additional challenge to wellbeing'. Absolute changes of fortune are less important than one's relative status - a pay rise will gladden your heart more if none of your friends gets one. Believing in God helps, but how do you legislate for that without bringing back the Spanish Inquisition?

The next day I speak to David Halpern, a senior policy adviser in Blair's strategy unit who co-authored a discussion paper in 2002 on happiness and how policies might be formulated to promote 'a more leisured work-life balance'. The first step, he tells me, is to decide whether life satisfaction is any of any government's business. 'I think it is, and most people on the street would say it is.' Everything is a trade-off, he says. 'If we can make 90 per cent of the people much happier and 10 per cent more miserable, would that be good or bad? You have to make a holistic judgment about what will contribute greatest to total wellbeing.'

Some areas are relatively easy. In unemployment, research shows the fact of being out of work affects an individual's wellbeing more than actual loss of income. So, in policy terms, he says, you should get people into work. But sometimes the research points to something else. 'The classic example is health, where the dominant variable is being treated with respect. In terms of satisfaction, it matters more than the objective clinical outcome. So do you get your hospital to maximise that outcome, or say that what matters is the subjective experience as well? And take the police. We know that how fast you get there matters less than getting there when you said you would. So if you take the subjective experience seriously, it has real consequences on how you utilise your resources.'

This new measure of subjective experience is emerging in policy papers. 'It's a more credible area, as people have seen the reduced utility of income to increased wellbeing. But ministers have been cautious. If life satisfaction hasn't moved for 30 years, you need to see an intervention that works, be it with old people or kids - a better version of Making Slough Happy. That becomes the moment politicians say: We can do this, which costs X and leads to Y as a result.'

So, I ask, when do we turn into Denmark?

'The one thing that hasn't crystallised yet is: what are the politics of it? What are the big collective choices you have to make as a society? Put it this way: if you've got David Cameron versus someone else, what kind of argument will they have? Some of it will be around equity, distributional issues. But it hasn't fully matured. No one quite knows what they're offering.'

So what's the best way to get happy? Changing the way we look at the world, or the world itself?

Nick Baylis is wary of the current political interest in wellbeing, suspecting it may be just a fad. Nor is he a fan of TV shows that trivialise positive psychology by equating it with 'positive thinking'. He describes Making Slough Happy as 'monstrous drivel' and says The Happiness Factor was full of quick little fixes. 'Why not spray lavender on your pillow at night! Then there'll be some presenter pulling up in a Ferrari and saying: "You might think driving one of THESE is going to make YOU happier. You'd be WRONG. Science proves that it's NOT." Cut to girl with clipboard handing out questionnaires. I just sat there going, "Oh my God."'

We are sitting in his front room - the nerve centre of Cambridge's Wellbeing Institute. At first glance it's a typical don's lair - comfy sofas, a cluttered desk, cake and tea - but, where one might expect to be surrounded by academic tomes, memoirs by David Beckham, Betty Boothroyd, Bruce Springsteen, Julia Roberts stare down from the bookshelves. These are among the dozens of public figures Baylis identifies as having the right stuff in terms of steel, passion or resourcefulness - lives whose fighting example he has distilled in his wellbeing manual, Learning From Wonderful Lives. The book is a hybrid of styles, combining the tropes of self-help guides - lots of capital letters, exhortative chapter headings, pepperings of Dawn French, Bill Gates, Einstein - with scientific theory. Baylis is lucid and convincing - inspiring, even - but some uncharitable part of me still asks whether I can learn anything from Alan Titchmarsh. And if I do, will I end up talking like someone who has had a personality transplant?

'Happiness' scientists distinguish between 'hedonic' activities - drugs, shopping, TV, junk food - and the Aristotelian notion of 'eudaemonia', the life truly well lived, as rehearsed in Baylis's evidence-based skills manual: developing a purpose, mentoring, becoming an expert in something, battling fatigue, escaping from negative patterns. It seems the best sort of happiness is to be had by giving up the worst sort of pleasures. I can buy that, but do we have to bring Anita Roddick into it? Or Tom Cruise? It may be a coincidence that some of the most determined and pluckiest and positive people alive are also some of the people I'd least like to be trapped in a lift with. It may be I am beyond help.

It works for Baylis, though. 'I looked at people who came from more difficult backgrounds than mine to become summa cum laudes or Olympic athletes, and I said: How did they do that? I began to learn, to pinch some of their strategies, and say to myself: Yes, this looks grim, but what would Lance Armstrong do?'

Finding out how people got where they are is a habit he acquired doing voluntary work at the Feltham Young Offender Institution in Middlesex. His research, comparing the lives of inmates with kids from equally tough backgrounds who ended up with respectable careers in the Grenadier Guards, fed into his eventual doctoral thesis at Cambridge, which identified fantasy and escapism as a core element in the lives of young adults who go off the rails. He recognised this trait from his own unhappy boyhood, in which fear was 'the dominant emotion'. A single incident (being shouted at by a teacher) left him with a stammer for years, though he doubts that was any more than a trigger.

Baylis scraped through school and left university 'in tears' with a third in psychology. After a stint waiting tables, there were fruitless attempts at writing fiction (he did the masters course at UEA) and film studies (NFT) before pitching up at Feltham to start a creative-writing programme for inmates. 'I was comfortable among prisoners. Like me, they were scared of reality, but just dealt with it more clumsily.'

I ask if he'd been born into a different class he might have ended up behind bars. 'Without a doubt,' he says. He got into criminology (with the Open University) and back into psychology at Cambridge. But his doctoral thesis was stalled by examiners who questioned its status as psychology. With no obvious way out, Baylis contacted a Harvard professor of psychiatry, George Vaillant, after stumbling on his 1977 book Adaptation to Life - a study of lives that had gone well. (Baylis simply phoned Harvard, not even knowing whether Vaillant was still alive. 'Amazingly, he answered the phone!'). Vaillant came to Cambridge, examined his work and became his mentor. Positive psychology was just taking off in America - another stroke of luck. 'Suddenly I'm part of the PP thinktanks and I'm flown off to the Gulf of Mexico for a week-long conference. Suddenly I was no longer Nick Baylis rattling around, but part of the emerging positive psychology movement.'

That was in 2001. But the British psychological establishment has been slow to embrace positive psychology. So it was 'a million-to-one chance' that in 2003 Baylis and Felicia Huppert (his key ally at Cambridge) persuaded the Royal Society to finance a two-day world conference titled the Science of Wellbeing. Seligman was the key speaker, and the event gained widespread media coverage. In the wake of that success they launched the Wellbeing Institute at the University of Cambridge in 2006.

Baylis's own life itself sounds like a case history in the story of wellbeing. He seems to have had unusual determination. 'More like desperation,' he says. 'But these are universal skills. How we arouse our emotions and channel them. Use our minds to heal our bodies, bodies to heal our minds. Made simple, it's about how to improve your relationship with life. So I come to this not as an intellectual or an academic. I do it because it's absolutely heartfelt.'

Two days later, I'm back at Wellington College, sitting in on one of Ian Morris's wellbeing classes. The school only recently became co-ed so it's still all boys in Year 10, deep-voiced and vogueishly unkempt. The lesson today is excess, and Mr Morris hands out images of famous individuals who pushed themselves over the brink - Janis Joplin, Ayrton Senna, Kurt Cobain, George Best. Then he runs a clip from Britain's Biggest Spenders, a TV documentary featuring a week in the life of Scott, a young self-made millionaire entrepreneur who spends £100,000 a month on Lamborghinis and preposterous new suits threaded from real gold. What do we think of him?

No one sees Scott as a role model exactly, but there's some sympathy. One student pins down the 'class' question, suggesting that people with 'old money' don't splash it around like those who have earnt it and that we are perhaps too quick to condemn Scott's taste in diamond-encrusted watches. Another thinks Scott is 'on a high because he's still young'. Scott's money hasn't made him miserable - yet. These are bright boys and everyone gets the point.

But now there's barely time for a brief discussion on prematurely dead rock stars before the lesson ends. Afterwards I suggest to Morris that it didn't seem quite long enough. He agrees: 'It wasn't. What the course relies upon is a constant dripping tap, which is difficult when you only see them once a fortnight.'

The programme has been running a term and a half, so it's still a work in progress, but he is confident about its prospects, saying that it gives PSHE (commonly known as 'citizenship' lessons) a more distinctive framework. 'For some time I'd been looking for an overarching philosophy for PSHE, rather than just sex and drugs lessons, and this just landed on my plate. Nick's research is very clear.'

He agrees when I say much of it is just common sense. 'But there are other times a light will go on, and they'll say, "I never thought of that ..." So it's a mixture of them already understanding some bits but also seeing a new pathway through a particular aspect of their lives.'

Later, I wait for Anthony Sheldon in his grand office, surrounded by leather-bound volumes of Swift and Punch, along with biographies he has written of Major and Blair. He arrives slightly bemused, having read Toby Young's article in the Spectator pooh-poohing Wellington College's wellbeing lessons. 'Toby is lovely. He just needs to attend some of these classes. Learn a bit more about himself. He suffers from a disconnection from other people. He is a classic case of an intellectual who lives in his own head.'

I ask Seldon if he thinks the wellbeing programme gets a fair press. He says that generally it does. 'But a number of intellectuals have a problem with it. They don't understand it. It's not an intellectual thing. It's a developmental approach. The purpose of education is not just to cram your children through exams and then think you're doing a fantastic job. Yes, in our kind of school, where you have well-off, bright, motivated kids, hey presto, 90 per cent get As and Bs at A-level. But so what? That's not education. Education is taking everything it means to be a human being and developing all facets of it. That's where the wellbeing comes in.'

I ask where he gets his zeal for this spiritual approach. (His background offers no obvious clue - Tonbridge public school; Oxford; his father, the economist Arthur Seldon, was one of the architects of Thatcherism.) 'I had a very exciting childhood, adolescence, university, but in terms of me as a human being, it didn't get me where I wanted. I'd read philosophy, politics and economics, but it didn't mean very much. I wanted to find something that made me feel much more grounded.' He got into meditation and yoga, which he says 'helped centre me and give me a better sense of value'.

So should we be teaching wellbeing in all schools? 'Schools have a responsibility to help develop these qualities. Not just snotty public schools, but every school in the land. It's particularly important with children from less- privileged backgrounds that schools do this.'

Outside in the freezing drizzle I trudge down the drive. I decided to leave the car at home after Monday's fiasco and last night's snow, which now means a wet walk to the station and four trains home. On the upside, though, I can get a soothing cappuccino and a muffin at Reading, find a quiet seat and have a snooze on the journey. Oh yes. I take in some deep breaths. Perhaps I am already channelling my negative emotions. Last week I would have called it wishful thinking.