I don't recall when I first became aware of Tough Mudder, and the garish orange headband its graduates gain the honour of wearing.

Likes on Facebook perhaps, from a squaddie relative, or shared promotional videos of trained killers, gym beasts, hardmen and hardwomen emerging from muddy pits, breathless but staggering on, hurting but unbeaten. Whatever it was, this Tough Mudder thing was clearly not for me, an ageing, balding, limping, gerunding journalist with an expanding waistline.

Tough Mudder is a 12-mile obstacle course that badges itself as "probably the toughest event on the planet". It's hard to disagree. The obstacles' names are enough to get you slinking back to the sofa: Ball Shrinker. Death March. Arctic Enema. Fire Walker. The descriptions don't help: run through flaming bales of hay; crawl through mud under low wire; swing across greased monkey bars above icy water; run through live electric wires. All that's on top of a cross-country run, across terrain the organisers chose for its "interesting geographic features" that enable them to "build an extremely challenging and enjoyable course". Sounds like hell.

Tough Mudder, predictably, kicked off in the US in 2010 in the aptly named Bear Creek in Pennsylvania. Some 5000 people took part – about 4950 more than the naysayers predicted. Three years later it is a global phenomenon that has so far attracted more than 750,000 participants, and this year offers 53 events across the US, Canada, UK, Germany and Australia. Next year they're adding Japan, Netherlands, Denmark, Switzerland, New Zealand and a handful more. This beast has legs.

But it's a beast with a heart. Charity's a big thing for the organisers, and in the UK the main beneficiary is Help For Heroes. Its support for the armed forces helps explain the jaw-dropping videos of veterans – some of them lacking limbs or in wheelchairs – hauling breezeblocks or tractor tyres up muddy slopes. As well as war, another tried and tested way to prepare is enduring labour without pain relief. Don't believe me? Visit YouTube.

So when I was asked if I wanted to do the Scottish race along with 15,000 maniacs this August, I immediately said no, but something had captured my interest. The challenge, the daftness, the camaraderie, the excuse to get fit, stop smoking, eat healthy, do better, be more, live longer. Impress my children. All that. And when I discovered the race takes place on my birthday - well, that just sealed the deal. That and the orange headband.

Now it's just a matter of getting fit for the challenge.

The health warnings plastered over the event's website will alarm anyone who's not Rocky or Rambo. "Tough Mudder will punish you, no matter your shape, size or current level of fitness," one says. Sounds great.

"Each Tough Mudder course will have 10-12 miles of hills, mud, water, ropes, walls, electric shocks and fire designed to push you to your limit." Sounds marvellous.

"We encourage all Mudders to increase their physical training." Sound advice.

With two dozen nasty obstacles – invented by British special forces – jaunts on the treadmill and the occasional push-up aren't going to cut it, so Tough Mudder offers its own customisable training course to get you into course condition (fittingly, devised by an ex-SAS trooper).

The names of these exercises are as ludicrous as the obstacles. My favourite: the Turkish Get Up. Start by lying on your back, holding a dumbbell or rock above one shoulder. Then stand up tall, using your free arm to help you, but keeping the weight above you at all times. Lie back down, keeping the arm fully extended and straight (you can use your free arm to help you back down). If you can, repeat 10 times. Then do the other arm. It sounds bonkers, looks silly, and hurts like hell. Combine with limb-burners such as Log Bog Belly Bombers, Dirty Ballerina, Pull-Ups and Braveheart Charge for a robust workout. The website has about 25 exercises with which to create your own circuit, build up your strength, improve your cardiovascular function and banish any weakness.

However, nothing will replace the benefit of a hard run. Forget roads and easy tracks. Find broken trails, muddy paths and slopes for uphill sprints. Staircases get your calves burning. I've developed a 5km circuit around about work that takes in stairs, uphill sprints, goalposts for pull-ups, benches for tricep curls and raised push-ups. Go along verges rather than pavements: the dog dirt and broken glass force you into an uneven pace, simulating rough terrain. Zip along raised kerbs and low walls to boost your balance – vital for the Twinkle Toes obstacle.

With so much British special forces input, you also want to get a military philosophy into your Tough Mudder campaign, so make your training count. Make it hard and don't back down if a blizzard starts midway through a run. Instead, be grateful it just got a bit harder. Always take the muddier, steeper, tougher option. Sprint it in appreciation. Make brutal runs your new hangover cure. Tomorrow I'm going for my first 10-mile run. The forecast's foul and it'll probably blow a gale. There's a bit of luck then.

Tough Mudder takes place in Dalkeith on August 24 and 25. See toughmudder.co.uk for details.