I was out running the other day near my house and passing me in the other direction was a paragon of sheer human endeavour.

A man in his mid-50s was half-running, half-limping along, wearing a grubby yellow T-shirt that was dark with sweat and clinging to his impressive paunch. Just as we passed one another, a robotic 20-year-old who looked like he'd just stepped out of the Olympic village strode by, tanned, gleaming and barely breaking a sweat. For a second they were juxtaposed, the pneumatic young Apollo and the flailing baldy, and I have to admit I was impressed – by the sweaty one.

As someone who huffs and puffs while running and releases heat almost entirely through my face – going so beetroot coloured, people have been known to point and laugh – my affinity was entirely with him. I deeply admire anyone who, after years of being overweight, digs out their gym shoes, pulls their socks up and sets off to exercise among twentysomething gym denizens and running club regulars in body-sculpting Lycra. That is not an easy thing to do.

It makes it harder that some of us just can't exercise elegantly. By the end of a run my hair is a frizzy mess (sometimes, even before I start). So it encourages me to see other people cheerfully bowling along not caring a hoot that their shorts keep riding up their inside leg where their thighs rub together. I warm to the guys in the gym who turn up in pyjama shorts because what's-the-point-of-buying-something-new-when-these-will-do? Gyms are full of women with perky ponytails and perfect make-up. How silly is that? Surely the grooming should come after the exercise.

So here's to tatty T-shirts, scarecrow hair and mismatched socks. Not caring what you look like exercising is the first step to enjoying it.