Andy Pearson, the founder of London Parkour, maintains that anyone can do parkour if they want to enough. I have always seen it somewhat differently, as a kind of street version of Cirque du Soleil, suitable for only the skinniest kid with a death wish. Walking towards a cul-de-sac full of low walls, I am disbelieving.

“Even someone carrying a lot of extra weight?” “Yes, as long as you start with what they are able to do safely.” “Even the strongest man on Earth?” “Yes, as long as you allow for his muscle ratio.”

We come to some walls. Pearson wants to start with focus and flexibility exercises; warming up has never been more important, especially when you’re not 17. You can land pretty heavily even if you don’t fall off, and this is all concrete, remember. We do a fiendish exercise of rotating one knee while tracing a shape with the other, and rotating one wrist while drawing a box with the other. “It doesn’t look very much like a box,” he says, affably. I want to make a nitpicking point about the degree to which any shape made with a wrist resembles a box, but he is right; whatever its challenges, I suck at this. Which is a shame because, for some reason, I already love it.

You know how sometimes there’s a rail on a low wall, for no reason you could name? The basic starting point is to be able to balance on that rail with one foot. It sounds easy, but it ain’t. I manage 10 seconds on one leg, about six on the other. I’m beyond smug. It took about 20 minutes to achieve this.

The basic jump, meanwhile, is a step vault; one hand planted on a low wall as you go over it, the opposite foot lands on the wall; your inside leg tucks underneath yourself, and then you’re over. It’s not as easy as it sounds, but it’s not so hard that you can’t master it. There’s a lot of swinging round parking signs and scaffolding poles; it’s physical but not technical.

You could lose hours just making a routine and trying to speed up: step vault, swing round a pole, step vault, shimmy along a wall for a bit, jump off. It’s the least prissy of any sport I’ve tried; in this complicated urban structure – it looks like a car park, but it’s not big enough – we spend ages just toeing round railings, trying to get past pillars and bikes, hanging off scaffolding.

One minute I am covered in grease, the next in dirt. We climb laterally along a wall, inches off the ground, holding on to ledges. Anything that is too high to vault, you have to approach with a cat leap. Just run at the wall; as long as there’s something at the top to grab and your first foot places high enough, you’ll make it.

“That’s great, you’re actually bleeding,” Pearson says. It’s true, I have a tiny nick on my wrist. I’ve never been so delighted with myself and yet I don’t know how to get down.

What I learned

If you’re frightened to do something, try making it harder for yourself by closing your eyes. When you go back and try it the easy way, you’ll be able to do it.