A fat man goes for a run.

It’s a sudden impulse.

One moment it’s not a thought that’s ever occurred to him before. The next moment it’s a thought that has a occurred. More than a thought, an impulse, which must be acted on now.  It's the only thought that matters. It's an all-encompassing thought. Like the Devil in those old stories. One minute he wasn’t there, the next minute, he’d always been there. It seems suddenly that he's always wanted to go for a run, he just didn't realise it before.

All his life he has been overweight, to the extent that it’s been something he barely thinks about. A bouncy baby. A chubby toddler. A small boy with puppy fat. A porky teenager. A fat adult. He’s been these people, and, for the most part, he's been them cheerfully. These were all identities he understood, lives he could inhabit. But now he’s an obese middle aged man.

(That’s the word that’s done it. The word obese. He’s always known he was fat, but he’s never been particularly bothered by it, apart from a few years in his teens. But obese is something else altogether. Obese is medical. Obese implies joint problems, breathing difficulties. It whispers about tubes and procedures. It insinuates an otherness, a not-quite-rightness. And when his phone had downloaded an fitness app with out him asking it to, and when he'd filled in the details because he was a bit bored and maybe doing a fitness app might be fun it had used that word. And so he'd sat back in a sudden daze, wondering what it meant.)

And now, suddenly, as sure as he’s ever been of anything, he feels the need to go for a run. He wants to run until he’s not obese any more. He feels, no, he knows that once he steps out of that front door, that’s it, a new world awaits. He's certain of it. He can taste the future in the thought and it's full of wild promises.

He scrambles up the stairs almost on hands and knees and searches his bedroom for suitable clothing. He’s got trainers, he always wears trainers anyway. He finds a pair of tracksuit bottoms. He finds an AC-DC T-shirt, from when he saw them ten years ago. Pulling it over his shoulders he’s aware that it’s tight, too tight. Anatomically tight.

He looks further, deeper into drawers which are rarely unpacked. He wonders why he has so many clothes, when he wears the same few things most days. He finds a charcoal grey T-shirt. It still has creases in. He wonders when he bought it, or if he did. It’s the sort of neutral, tasteful piece of clothing that his Mum cautiously sends him each birthday, and at Christmas.

It’s loose enough that it provides him with a degree of comfortable coverage. He sighs with relief, the dream still lives. He’s ready, he’s going to go, it’s going to happen.

Almost falling down the stairs in his eagerness to get outside and begin his new life as a runner he gathers himself and takes a deep breath. The front door is a portal to a whole new world. A whole new way of living

If this were a story by Borges, it would happen the way he dreams. He would run and not stop, through day and night, across seas and continents, having countless adventures before arriving, years later, at his front door, transformed. A thin, taut man, weather-beaten but with infinite reserves of wisdom and compassion. He would have inspired others on his route, he would have run with saints, Popes and reality television stars, he would have become a celebrity and then sunk back into obscurity, and still he would have run.

Sadly for him, though, this is not a story by Borges, it’s a story by Matt Fallaize. And what happens is this: after taking an age to decide which direction to run in he starts. Gingerly at first but with increasing confidence. It's a sort of shuffle to start with but, gradually, by degrees, he begins to jog. He runs, no less, he actually runs for all of two hundred yards before, breathless, and with little red stars of pain bursting behind his eyes he clutches a lamp-post and heaves with unspent emotion for the life that’s led him to this point.

That’s not the point of the story of course. The point is that, despite the pain in his hamstrings and calves he tries it again the next day, and the day after that, and he gets gradually better. Two years after that first short, agonising jog he enters a local race and is amazed by all the encouragement he hears from people lining the course as he shyly shuffles round. He is still fat. He is still, technically, obese, but these people don’t seem to mind, they clap him, they cheer him on.

If this were a story by the younger Matt Fallaize, he would suffer a heart attack, or a muscular tear. He would curse himself for ever trying, he would hear the laughter behind the encouragement. Luckily, it’s a story by the older Matt Fallaize, who has hopefully learned a few lessons, and is a little kinder for it. He continues to run and, by increments, gets a little fitter, loses a little weight. He learns to love it, he comes to rely on it and, sometimes, on early mornings when the sky is liminal and the whole world a suggestible commodity, when coveys of grouse take sudden whirring flight, when dew still bends the neck of the fritillaries and mistle thrushes sing in interrupted phrases from the very tops of trees, he experiences feelings which come remarkably close to grace. And that will do, that will do just fine.