THE SPARATHLON WAS MY EVEREST , FOR 40 HOURS AFTER KISSING THE STATUE IN SPARTA GREECE , I CANT MOVE MY LEGS

They just follow me limply about, attached to my waist but utterly incapable of independent action. I haul myself where I need to go.

That first night, I flop onto the mattress, with my legs hanging over the side. And that’s how I stay, sleeping in the shape of a twisted right angle. The prospect of having to sit up and force my legs into a position where they’re not making my lower back ache is worse than the pain I already feel. I’m thankful that I’m too dehydrated to need the loo.

The following day, I muster all my remaining energy and crawl to the bathroom, slither over the edge of the bath and lower myself into the water head first. It takes an hour to get washed and dressed, and I’m proud I manage it so quickly.

I need wheelchairs to get me through the airports. At Heathrow my children are somewhat taken aback to see me so incapacitated. I suspect my wife is, too, but she’s better at hiding it. I’ve never been happier to see them.

We head straight to hospital, where I'm given a walking frame. Over the next few days, life slowly begins seeping back into my legs.

Meanwhile, goodness knows what I’m sweating out. I spend the first week sleeping on the sofa (the stairs being a challenge too far) and wake up every morning with the cushions soaking wet. We end up having to buy a new sofa.

And it’s while I am researching the sofa purchase online that it happens: my browser search history changes from ‘ London sofa shops’ to ‘ worldwide ultramarathons’.

When you run silly distances, the question ‘ why’ pops up a lot. Why run for five hours when you could stay in shape in 20 minutes? Why push yourself to extremes? Why isn’t a marathon enough?

Why choose a sport in which blisters are a badge of honour and suffering is mandatory? Why, when there’s little prize money on offer? Why, when even the very best endurance runners are not well known and most have to work proper jobs just to get by? Why, when training requires so many hours alone on the trail? Why aren’t you normal? That’s the heart of the matter. Are we really ‘mad’, like so many people seem to suggest?

Many years ago, I was told the following tale by my grandfather, as I sat on his knee one sweltering summer afternoon in the house he built by the sea. For a long time I believed it was ancient Greek wisdom, passed down from generation to generation. I liked

to think you could trace its origins back through the mists of our family, through Cretan mountains and remote island fishing ports, way back to the great Athenian empire, to the dawn of philosophy and civilisation. Back, in fact, to the original ultrarunners. To those legendary long-distance messengers such as Pheidippides.

As it turns out, it’s actually a Cherokee parable from Tennessee, US.

An old man is teaching his grandson about life. ‘A fight is going on inside me,’ he explains to the boy. ‘ It is a terrible fight and it is between two wolves. One is evil – he is anger, envy, sorrow, regret, arrogance, self-pity, resentment and ego. The other is good – he is joy, peace, love, hope, determination, humility, fortitude, compassion and truth.

‘The same fight is going on inside you – and it’s going on inside every other person, too.’

The boy thinks about it for a minute and then asks his grandfather, ‘ Which wolf will win?’

The old Cherokee smiles and replies simply, ‘The one you feed.’

And that’s the point of this, really. All this endless running. All the wonderful people who enter all these stupidly long races knowing they’ll frequently fail to finish. All the pain they suffer, all the injuries, the failures. All the lost toenails.

But also the successes. The feeling of having pushed yourself to the edge of your limitations – and deciding not to quit. To push on regardless. To keep on running. The satisfaction of helping a fellow runner in trouble; the comfort of being helped. The lifelong friendships formed. The exhilaration of getting your body to achieve the impossible. You break yourself down, like stripping an engine, yet emerge more whole.

Training for and achieving a desired time can be enormously rewarding. For ages, my holy grail was a marathon time starting with a ‘2’. Pulling that off remains one of my proudest moments. But the journey as a whole, while satisfying and eventful, was never especially joyful. Definitely not the training, and not many of the races, either. Running on the trail, on the other hand...

I don’t much like the word ‘ultrarunning’ because it sounds exclusive, which is the opposite of what it should be – and is. Endurance running is inclusive and quietly seems to make you a better version of yourself. For me, and so many of the runners I’ve spoken to over the years, running long gives a powerful sense of joy and serenity.

There’s the warm blanket of community, too. The generosity and positivity of runners and volunteers, as well as supportive, long-suffering friends and family behind the scenes. Out on the trail, there’s the slow accumulation of problems, and the even slower process of solving them one by one. You’re in the moment. It can be like therapy, or an exorcism. A journey of self-knowledge. You’re feeling liberated from daily life but you’re also taking control, escaping into a more simple world.

I’m a father to three terrific children. When each of them came into the world, I experienced a deep sense of contentment that stuck around for weeks. It seemed like everything was going to be OK and that nothing could burst my private bubble of joy.

When I finished my first 100-mile race, I felt that same elation. For a month, I told everyone who’d listen how amazing it is to run 100 miles in one go. How they should try it.

And so they should. I know it sounds like a long way and, of course, it is. If you’d told me five years ago that I’d be running these silly distances, I simply wouldn’t have believed you. But it comes in stages. First- ever run, then first 5K, 10K, half-marathon, marathon...and anything beyond is an ultra. Just build it up slowly.

Reaching the finishing line is exquisite. Life-affirming and renewing. But the journey can be so very tough, and the urge to stop almost overwhelming. So why do we put ourselves through it? Simple, really. We’re feeding the good wolf.