Presenter Ben Fogle admits he was drunk when he volunteered to take part in the Marathon Des Stables, a 150-mile run through the Sahara, but, as he tells Sarah Waterfall, the race had an unexpected bonus.

When Castaway's Ben Fogle starts talking about his preparations for the infamously arduous Marathon Des Sables - a gruelling 150-mile run through the Sahara Desert - you can't help but smile at his less-than-sophisticated preparation.

''It was a drunken bet,'' giggles the impeccably-spoken 30-year-old. ''Friends were talking about enrolling in the London Marathon. I said that everyone runs that one and I'd like to do the Marathon Des Sables, if I did anything.

''So, in a hungover state I enrolled and forgot about it. Six weeks before the race I got a call to say that a place had come up.''

The punishing race, which takes place every April, involves carrying your own food, rationed water supplies and sleeping in Bedouin tents en route. People have died during previous events.

For highly fit, athletic types, short notice wouldn't be an issue. Ben, however, had done no training whatsoever when he received the call.

''I had never run any distance at all, never done any sport. My diet consisted of far too much coffee and food on the move. I wasn't even a gym-goer.''

At this stage most sane people would back out realising they'd drunkenly bitten off far more than they can chew - but not Ben.

''My parents said they genuinely didn't want me to do it. When I finally turned up at the gym they said, 'Don't even try it'.

''I had too much pride to back out. If I make a gentleman's bet, I have to honour it. I'm a stickler for those things. I didn't listen and decided it would make a great documentary.''

Since Ben rose to fame four years ago as the cute, posh picture editor in reality show Castaway, he's presented Countryfile, Animal Park and recently completed One Man And His Dog, which will be on our screens over Christmas.

''I've been an ice-cream scooper, a barman, a picture editor, in the Navy and spent time on conservation projects in Latin America. I've done my presenting and writing but the thing that excites me is combining all of that with great challenges.

''I was filming most days at Longleat for Animal Park,'' he explains of his last-minute training schedule. ''So half of my training involved running the perimeter of the lion enclosure, while the London-based half saw me running around Rotten Row in Hyde Park. It was the only sandy place I could think of.

''The Sahara's so hot at that time of year that you're actually advised to take a treadmill into the sauna. My local gym weren't having any of it so I just had to wear lots clothes.

''At the same time I set up a production company called Rambling Ruminations. I had to do all of the organising for permits to go out to Morocco, as well as Land Rovers and helicopters and things.

''The fact that I've managed to strive as an independent and get a commission, what with everything else, is one of the things I'm most proud of.''

It's a feat that only a lunatic would take on, but Ben says the experience has not only produced a fascinating documentary, but also given him an incredible boost.

''When I came back I had more confidence than I've ever had. For 12 hours each day you're out on your own, hurting more than you've ever hurt before. There's one section where you have to run 50 miles in a night. Can you imagine? You follow a big laser in the sky but you're running through 200 metre-high sand dunes.

''Most runners had been planning for years and took clever, sophisticated food. All of mine was bought from Marks & Spencer and weighed about a million pounds.

''Because of the heat and the weight of your pack your feet swell to two sizes bigger. Sand goes into your socks and turns them into sandpaper. My feet were the most disgusting thing you've ever seen. If you lose more than two layers of skin from that you're thrown out of the competition. And if you need more than two IV drips for dehydration then you're pulled. I had one.''

''At the finish line you're all completely broken. I've never seen more tears in my life. I cried, everyone does. I'm embarrassed to admit to that now but at the time you can't control yourself. I came in the late 100s. It's all about finishing, not where you came.

''Afterwards I spent a day in hospital in Morocco with blood-poisoning from the sand and a week on crutches.''

The event, Ben reveals, was also partly responsible for landing him his current sweetheart, Vanessa Nimmo from Big Brother 5.

''I'm the shyest person when it comes to girls,'' admits Ben. ''Practically every girl I've ever been out with has made the first move. It was probably the first time in my life that it was the other way around.

''That's the sort of profound change The Sand Marathon had on me.''

* Ben Fogle's The Sand Marathon is on BBC2 on Saturday, 2.45pm.

Published: 28/10/2004