Tough Mudder events became famous as the kind of thing that other people did – young people, crazy people, people who liked to run, but who shuddered at the idea of the “fun run”, because fitness shouldn’t be fun, it should be tough.

To this end, runs were devised with obstacles in between. They made you muddy, but they also – in the hardcore 10km or 10-mile versions – gave you electric shocks. You did them with team-mates, and everyone helped each other, and it was very bonding. It is more within my capabilities, but more alien to my outlook than the triathlon or the marathon – a kind of Sports Relief or Red Nose Day for grownups; excessive physical exertion combined with enforced camaraderie.

I went to Bristol, partly for a change of scene, partly because it was a 5km and therefore, technically, a mini-Tough Mudder. You can join in without a team, but this would involve helping strangers, which I’m fine with, but also asking strangers for help, which is about as close to my emotional boundaries as I can imagine – worse than an electric shock.

The Downs were beautiful, but the infrastructure overwhelming: fizzy drinks reps and comperes shouting comical motivational slogans at the start line. There are obstacles that you couldn’t even contemplate without a partner, so I made friends with Dougie. He was a minister at a United Reform church, and his mates from Christian Aid hadn’t turned up. We set off.

One kilometre in, we came to the Devil’s Beard, a low-slung, wide-spaced netting that you had to crawl underneath. We ploughed on, another half kilometre. An obstacle of a giant spider’s web that you had to climb over slowed us down, but didn’t deter us. Some hay bales were scaled quite easily. Another kilometre; then the wheelbarrow, one person holding the other’s ankles while they hand-walked along, then switching. We didn’t have a hope, and skipped it. This put us quite close to the front, and when we got to a Hero Wall, I was congratulated for being the first woman to pass.

I was thrilled, even though I knew I’d cut a corner, and there’s a lesson in there somewhere about the mechanics of self-delusion. The hanging hoops were way too hard; Everest was a rubber wall that you run up which we both managed; but the pyramid was just stupid for a team of two: a sheer frictionless wall that, in principle, you would climb on your partner’s shoulders, and he would scale up and climb on yours. I can see it working if there were 15 of you, and the ones at the bottom were prepared to suffer the indignity of never making it.

The obstacles are all very army-like, and Help for Heroes insignia flies high. I have nothing against the army; I do have some residual suspicion of people who like to pretend they’re in the army. “This seems to be mostly about drinking,” Dougie said, referring to the free cider that awaited everyone at the end.

We were both way out of our comfort zone. But the exercise euphoria kicked in. I finished sky high, and chatted to some travelling railway engineers all the way home as if I were at a cocktail party.

Give it a go

Find your nearest race at toughmudder.co.uk and muddyrace.co.uk. Zoe wears Merrell’s limited edition All Out Crush Tough Mudder 2