Tim Dowling
Real age: 49. The age I feel: 39

I doubt many people over 40 feel as old as they look. For most of us, the face in the mirror is the painting in the attic. When I haven't been in front of my reflection for a while, I forget what my age looks like. The face I imagine I'm peering out from behind is about 10 years younger than the one I catch sight of when my computer screen suddenly goes dark.

It's hard to gauge the age I feel inside: the actual person – a frightened little homunculus – doesn't change much, but the person I'm pretending to be has to recalibrate himself constantly. Maturity is a pose I can manage from time to time only because I know the outer shell is weathered enough to pull it off. Wisdom is easy: look old, say nothing. At the same time, I find that giddiness or irreverence may cause alarm in strangers. If I'm going to play to – or against – the stereotype of someone my age, I have to bear in mind how old I am.

I learned some years ago that what is commonly called a mid-life crisis would be better termed a personal ongoing emergency. In my case it never reached any sort of "crisis"; it just kept getting worse. I have long since given up on the idea of being comfortable in my own skin. I never have been, and I can't see how encroaching infirmity is going to help.

Mine is a generation that believes it is the first to refuse to be circumscribed by middle age. We'll just carry on as before, we think, unhampered by respectability or decorum. I'm pretty certain every generation felt this way – at least with respect to the preceding generation – and thought it was the first to do so. But the restrictions you fear middle age will impose upon you simply aren't in place. At my age, one is free to behave like someone 10 years younger, or 10 years older, and embarrassment is the least of all terrors. You can be anything you want at 50, except cool.

I suppose if I had to put a number to it, I'd say I generally feel about 39. Except on the morning after a long-haul flight, when I feel 100.

Michele Hanson
Real age: 70. The age I feel: 18

How old do I feel? It varies. Mentally, I feel between 11 and 18, masquerading as an adult. It's a bit scary, because there's always the risk that I might get found out. Someone might realise that I am not a proper grownup. Even though I'm 70 and a half, maturity never quite happened. But with a bit of luck, people will now confuse it with the sixth age – childish, but not quite at the sans teeth, sans eyes and all the rest of it – and they won't guess I never progressed in the first place. I still like Jackie Wilson and Wilson Pickett, I still wear jeans. I'm pretending old age isn't happening, and in my head it isn't.

Physically, it's also very up and down. If I'm well and the sun's shining, then I feel about 40. I can even run about, sometimes more than I could in my 50s, because of all the practice I've been doing on dog walkies, but if I'm poorly I feel about 103, and if I look in the mirror without my clothes on, then also over 100, rather like a Struldbrug, those poor, tormented creatures in Gulliver's Travels, who grow old, stay old, and never die. Everyone dreaded being a Struldbrug, and I can see why, looking at my drooping, crinkling reflection and yellow dagger toe-nails, which I know will only get worse. So I just take care never to look. But in dim lighting, fully clothed and just after a visit to the hairdresser, and if I remember to stand up nice and straight, I'm 40 again. In the cold, clutching a hot-water-bottle with the bed-socks on, I'm an old lady.

I try hard not to fall over, because sprains, bruises and breaks take longer to heal and remind me that I'm on the road to death and getting closer and closer, at rather a worrying speed. Then my friends start to peg out, or have close shaves, which means lots of hospital visiting, and I'm back up to 90.

But yesterday the sun came out, I climbed a big ladder, on to the flat roof, and sprayed a tree in a sprightly way, had a lovely immature rant about the way the world is going, swore horribly, put on my favourite zebra-patterned shoes, had a dance, both legs worked rather well, and hey presto – 18 again.

Lucy Mangan
Real age: 38. The age I feel: 35

My parents' friend Jenni always used to say I was born 35. I think that's about right. I never enjoyed being a child – I have always been hopeless at the kind of energetic optimism being young requires. I looked forward to the days when an evening's socialising would mean a dinner party rather than being dragged to a nightclub and, better still, when most of the time nobody would expect me to do either and I could sit at home with a book instead.

So the closer I got to my inner age, the happier I became. And though real time has now overtaken it, I'm still in its vicinity and more than content. Being good at being young must be awful. Imagine your happiest years being over before you even knew you had them, before you were old enough to appreciate and enjoy them for what they were. Imagine living a life in which every moment takes you further and further away from your glory days, all your favourite memories receding into an ever more distant past. Imagine being able to say by the age of 18 that your best days are behind you. That seems a high price to pay, even for the most sociosexually adventurous and exultant of teenage years.

I am biased, of course, but being naturally middle-aged seems to me the best of both worlds. The happiness of coming into your kingdom is not so far away as to be unimaginable – even if you first become conscious of the fact when you are not yet allowed to choose your own shoes. It is not so far off that you cannot start to look forward to it immediately.

And then, once your brief period of prime time has passed, when your inner and outer worlds align and you at last find yourself at one with both yourself and your chronological peers and can start breaking out the good china, napery and Ottolenghi, you are not so far from death that your memories will start to turn on you. They will remain near and vivid enough to revive and refresh the spirit rather than so long ago and far away that they become like a patch of dimly glowing embers too far away to warm the heart and kindle happiness anew.

So, up yours, youthful, energetic, optimistic interiors. We lifetime middle-agers win in the end. Up yours.

John Crace
Real age: 56. The age I feel: 56

Is there a right way of feeling 56? I assume there must be if so many other people are confident about stating how old they feel; but if there is, it escapes me. How should a 56-year-old feel? Happy, sad, grateful, tired, terrified, dull, hopeless, out of my depth, experienced, stupid? At times I feel all of these things. Then I always have.

My mother is 89 and I know I don't feel the same way as her, so I'm fairly confident I don't feel 89. Except she may feel as if she's actually 95 or 83. So how would I know? Comparisons are all I have to go on. When my dad was 56, he seemed quite old to me. A bit sedentary. A bit dull. Dependable. But that's how most 56-year-old dads have always seemed to a 20-year-old son. I'd say that's how my 17-year-old son views me. Even down to the dependable. Amazing, isn't it? Where did he get that impression from? But I've no idea how old my dad actually felt because I never asked him. I don't even know whether he wasted much head-space wondering whether he felt older or younger than he was.

It seems unimaginable to feel younger than I am. How would that work? Which bit of the titanium in my knee, the bald patch on my head and the lines around my eyes do I choose to ignore? More significantly, which years do I erase from the memories that make up my collective experience if I claim to feel 40? Why would I even want to feel 40 again? That was roughly the age I was admitted to a mental hospital.

Nor does it seem anything but absurd to feel older than I am. How would I have managed to gain time? What memories have I now missed? It also feels presumptuous. How could I possibly know what it's like to be 60? I do feel quite old. But I am quite old. If I drop dead tomorrow, no one's going to say I died tragically young. Younger than I would have liked. But not tragically younger.

All of which is a roundabout way of saying I suppose this means – by elimination, if nothing else – I must feel 56. Ish. I don't imagine I will feel much different in six months' time when I'm 57, but you never know. Whether I act my age is another matter entirely.

Katharine Whitehorn
Real age: 85. The age I feel: no particular age

Depends what's happening and which bit of me I'm thinking about. I've plainly passed the crucial moment when you try to pretend you aren't old and start cashing in on it instead; I feel old when I need to hold on to handrails, sit down for a coffee I don't really need for the sake of sitting down and realise I know my physiotherapist better than my hairdresser; and I have taken to quoting someone I met who was also drinking long before noon who said: "The closer to the grave you get the less the rules apply." But when it comes to work I don't feel any particular age – unless the question of what I remember comes up. The time I was sent to interview Mrs Thatcher when she was still education minister, for example, and I thought I had better record it; but of course didn't manage the machine and had to go back and say the story didn't make; or going on her China trip ages ago – a female leader, better send a female journalist. The one thing that totally divides me from today's young and always will is the way those who grew up with computers and iPads and so on understand them in a way that people my age rarely do. My mother said that her generation would always be better drivers than her father's generation, because they had grown up knowing about cars; I feel the same about the new technology – that is the worst age division so far as I'm concerned. So if this piece never actually reaches the Guardian, they will probably be quite right to say: "Poor old thing".

Bim Adewunmi
Real age: 30. The age I feel: 20

I first left home when I was 10 years old. I packed a suitcase, a mattress, a pail and other Nigerian boarding school paraphernalia and joined my older sister, three years ahead and infinitely wiser. Almost a decade on, I left home again, this time to live and work in America. I was 19 going on 20, yet to start university and filled with the kind of blind confidence that only erodes with time and accumulated experience. That is the age I feel, still. It is the age that sometimes embarrassingly slips out when someone asks me how old I am. It's the age that engages my mouth before my brain: "How old are you, Bim?" "Twen– I mean, 30. I'm 30 years old."

Everything changed by the time I was 20. I had the beginnings of a grownup life: I was working in two not-very-nice retail jobs – squirreling away most of my earnings to finance the American Dream – and attending admissions interviews at universities. I took a pottery class at a nearby college, and volunteered at a youth project. I worked on a horse camp in California alongside other young people from across the world, and for the first time, friendships didn't have the shimmery, intense insta-burn of youth; we were grownups. We got at up at dawn, shepherded our charges to feed the horses, then breakfast, then whatever else we had planned for the day. I had young(er) people look at me like I was a real adult, and it was earned, not just by default. I travelled through chunks of America, in groups and alone, with my own money and at my own pace. I felt independent and genuinely carefree.

The feeling of adulthood solidified when I returned home to start university that autumn. I loved being 20. Twenty is when I began to step comfortably into myself, when I took charge. I don't want to ever let go of that feeling. Twenty is how old I feel. Why? Physically, I am much the same, although my insomnia is now ferocious, and my glasses prescription worsens with every check up. Mentally, I feel as if I am only building on what arrived, fully formed, at 20. Will I still feel this way when I hit 40, or 50? How about when I'm someone's mum? I'm not sure. Perhaps parenthood will briefly advance how old I feel before settling back down again sometime after the babies leave. Or maybe I'll stay exactly the same, forever 20 in my mind.

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