If you made a new year's resolution, the chances are you've already broken it. You may have slumped in your armchair, slurped on a large glass of wine and told yourself there's always next year. But don't give up so easily. Most resolutions are about trying to get healthier and you don't have to do anything drastic to get there. Here is our failure-proof guide to tweaking your lifestyle and ensuring that your new regime isn't just for January.

Don't join a gym

Not joining a gym won't make you healthy. But it will stop the false belief that you've achieved something. Dr Domhnall MacAuley, former editor of the British Journal of Sports Medicine and visiting professor of sport and health at the faculty of life and health sciences at the University of Ulster, believes a stepwise approach is best. "There is a lot of evidence to show that it's the people who do nothing at all who benefit the most from just doing a little bit. The biggest benefit comes from getting off the couch. Then you need to start walking: it's the best exercise for the cardiovascular system. Walk to the next bus stop along to the one you would usually catch the bus from. Take the stairs and don't park your car as close to the supermarket entrance as you can. If you say you'll go jogging three times a week, there's no way you'll achieve it, but if you make exercise part of your life, you're less likely to drop it as an optional extra."

MacAuley suggests setting yourself a target. "Maybe aim to do a 10km half walk, half jog," he says. "It was part of our Olympic bid to get people to be more active. The Olympics should encourage us to set our own goals for fitness. But we should remember that Olympians are the equivalent of the Ferraris of the grand prix circuit and most of us are family saloons, so there is no point comparing the two."

You shouldn't confuse getting fit with losing weight. "You can't use it to lose weight without restricting your calorie intake," says Macauley."You can get fit irrespective of how fat you are. Exercise reduces strokes, surveys show it may reduce breast and colorectal cancers and there is some evidence for it improving your mood. It is much better to think of exercise as a family activity. Walk the children to school, go swimming or cycling together."

Degree of difficulty Easy. You put one foot in front of the other. And repeat.

Have two alcohol-free days a week

Forget detoxifying yourself by having an alcohol-free January. There's no evidence that it does any good, and it may encourage you to drink more for the rest of the year. Instead, as echoed in a report published this week by the House of Commons science and technology committee, it is better to abstain frequently (although there doesn't seem to be evidence to support this either). "I tell my patients to go without alcohol for two days a week," says Dr Kate Adams, a GP in Hackney, London. "Too many people drink too much and it is easy to slip into bad habits and drink every night. What patients tell me is that they notice how clear their head is the next morning if they haven't had a drink the night before. Everyone I see who gives up drinking for January is miserable. It's all about moderation."

Degree of difficulty: Easy, unless you have had a tough day at work, or get tempted after the children have gone to bed. Then it's moderate.

Don't eat between meals

Try to avoid a gradual build-up of extra kilogrammes. "Don't eat between meals," advises Adams. "Eat healthily and if you have to have a snack bring in fruit. Only lose one or two pounds a week. Make a few small changes – do not feel you are denying yourself."

A series of papers published in the British Journal of Cancer last month looking at how lifestyle choices increase the risk of getting cancer, showed that being overweight or obese contributed to a number of cancers including colon and breast cancers that occur after the menopause. "The percentages we put in the papers for the contribution of lifestyle to the development of cancers are for populations and not individuals," says Professor Max Parkin of the Centre for Cancer Prevention at Queen Mary University of London who authored the research. "But they do point out the relevance of lifestyle and where you can as an individual change your odds of shortening your life."

Degree of difficulty: Radical (or we'd all have done it by now).

Exercise your brain

There is some evidence, but it's not conclusive, that brain training may ward off dementia by improving cognitive function – enough to spawn a multi-million-pound market in brain exercise products such as Nintendo's Brain Age. But you don't need to spend a lot. "I do a Sudoku puzzle every day," says Adams, "I don't know if it improves my cognitive ability but it stimulates me and gives me a sense of wellbeing, both of which are also good at reducing stress." Doing crosswords or learning French makes your brain better at doing these specific tasks, rather than having a wider effect on your brain's ability to retain and re-use information. There is evidence that being sociable is good for your mood and may delay dementia.

Degree of difficulty: Easy, although it does depend on the puzzle.

Watch less TV

A study in the British Journal of Sports Medicine found that on average every hour of television watched after the age of 25 years reduces your life by nearly 22 minutes. The effects are felt through heart disease, largely due to the fact that watching television is a sedentary activity, and we all sit too much anyway. But it's a good excuse to switch off the TV.

Degree of difficulty: Moderate, if you have a remote and are willing to use it.

Get enough sleep

Enough sleep is around seven to eight hours a night, according to the Loughborough Sleep Research Centre. The effects of not getting enough sleep may be exaggerated, they say (don't believe sleep debt causes obesity), but if you frequently feel tired by the early evening, have an afternoon power nap for 20 minutes and it will revive you.

Degree of difficulty: Moderate, although it is hard to take a nap in many jobs.

Give up smoking

If you are one of the one in five people who still smoke, pack it in. "No lifestyle change is as important," says Parkin. "There is no point fiddling with the fibre you eat if you are smoking. It can lop 10 years off your life on average."

Degree of difficulty: Easy, according to Parkin. Grit your teeth for a month.

January is grim enough without punishing yourself for the excesses of last year. Slow and steady wins the race, so choose some realistic goals and by next Christmas you'll be in good shape to over-indulge all over again.