The starting point for this programme began at one of the world’s most unlikely running races. In 2008, I found myself reporting on an event that even now makes me shiver when I remember it. Filming the North Pole marathon is a day at work you do not forget easily.

It was an experience unlike any other. An ice sculpted landscape backlit by an otherworldly sun that never set and yet struggled to provide any respite from the numbing cold. It was a huge challenge to keep our camera kit in some sort of operational order and a big physical effort to keep our bodies functioning in temperatures of -30. And we had it easy. We were just standing around filming. Everyone else was in the Arctic to run a marathon, which is a hard enough challenge in the most perfect of running conditions – this band of merry boys and girls were confronted with anything but.

Imagine running in a deep freezer that has been placed inside a wind tunnel that has been placed inside an even colder deep freezer. And then having a microphone thrust in front of your face every few kilometres by an Al Jazeera reporter inquiring as to how you might be feeling. What amazed me was that nearly all of them claimed to be experiencing some sort of perverse enjoyment.

In the weeks of defrosting that followed, I made a few promises to myself. I wanted to start answering as well as asking some questions about running. I would make plans to run my first marathon in as wild a place as possible. And if I ever returned to the North Pole I would pack an extra couple of pairs of thermal socks.

Five years later, I had finally got myself fit enough to run a marathon. I decided not to make a return to the North Pole, but instead entered the Antarctic Ice Marathon. I was hoping this shift out of my comfort zone would give me at least some chance of appreciating the mind-set of serious marathon runners. It also presented me with an opportunity to ask why, for so many of us, running in all its forms is the sport we choose to do.

En route to the ice, I travelled to some parts of the world that, thankfully, do not deal in permafrost. I went to East Africa to try and find out why, when I watch a marathon on TV, more often that not it is a Kenyan out in front. We also filmed at the New York marathon to ask why those of us who are never likely to win a race still think it is a good idea to put ourselves through 42.195km of relentless physical effort. Then it was to Chile, to meet a group of runners who had decided a volcano was a good location for a marathon. Yep, a volcano.

We also documented my own progress, or lack of progress, as a runner over the six months of filming. In all honesty, I started slowly and never got much quicker. But I did find some previously untapped reserves of determination. The Antarctic Ice Marathon would prove to be the biggest physical challenge of my life. That is something I had expected. What I had not predicted was the race becoming about so much more than getting fit. Training for it and finishing it did push my body, but more interestingly it took my mind to places it had never been before. My intention had been to try and make sense of why it is we humans seem to want to run. What I discovered was that for every runner there appears to be a different motivation. Running revealed itself to be that rarest of sports, where the rules are yours to write.

Four of the five fastest ever marathons have been run by Kenyans. As good a place as any to start training for my first. It is also a very handy place to interview some of the world’s best distance runners. In this country of running champions, the town of Iten is its unofficial capital. Some are born here while many more are drawn here by the promise of training with the best. I can’t hope to ever run like a Kenyan, but I can at least start to try thinking like them.

During our week of filming I get the chance to meet Wilson Kipsang, one of Kenya’s finest. A few weeks after I talk to him, he will break the marathon world record in Berlin. Wilson’s voice rarely creeps above a whisper but his words have a huge impact on me. “What gives you power, the courage and faith that you can really do something in a race, is how you have really trained. Whenever I was in a race knowing that my training was very good, no matter how hard it is I always keep on pushing knowing that I can do it.”

It really tells me everything I will ever need to know about preparing for a distance run. It will involve a lot of hard work and no small degree of pain. But I am also reassured that my desire to run a marathon and be the best I can within my considerable limits, are at least understandable instincts. It is time for my training to get at least semi-serious.

My first-ever organised run is in the relaxed setting of Key Largo in Florida. With just over two weeks to go until the Antarctic race, I enter myself into a half-marathon. Word has got out that a strange Englishman will be running in what is a low-key community event. The emphasis here is on fun and not, thankfully for me, elite performance. My date with the ice is formally announced by the race starter just before the run gets underway. The news is greeted by my fellow runners with some bemused head shakes and a few consoling pats on the back.

The run itself goes okay. The weather is warm, the course is fairly flat and I finish in a little under two hours. My spirits are further lifted when I discover that I am the fastest in my 30 to 39-year-old age group. Those same spirits then all but evaporate when, on closer inspection, I discover that a 65-year-old man, a 50-year-old woman and a 12-year-old boy have all ran faster than me. My parents, who are on holiday nearby, are waiting for me at the finish line. I convince them to talk on camera and try to get a few words of encouragement out of them. I ask my dad what chance he gives me of finishing the Antarctic marathon. “Well to be honest son, nil,” is his deadpan reply.

Chile’s Atacama desert is a far from obvious place to stage a marathon. It is the world’s hottest dry desert. It is also at high altitude, meaning that oxygen is in short supply. There is also no shortage of active volcanos in the vicinity. But it was those very factors that convinced race organiser Richard Donovan this would be a good idea.

The Irishman has turned extreme running into an art form. Arguably Richard’s greatest achievement came in 2012 when he ran marathons on each of the world’s seven continents in less than five days. He admits his latest venture is counter-intuitive but that it is the very promise of adversity that has attracted an adventurous band of runners to take part in the first-ever Volcano Marathon.

This run is less than a week before the Antarctic marathon so I am aiming to complete three quarters of the course. The start line is at an altitude of almost exactly 4,500 metres. That is not far off the height of Everest base camp. It is both breathtaking in its beauty and in a very literal sense. At times it feels like I am running while somebody is standing on my chest. These are almost perfectly brutal conditions. A shortage of oxygen, an oversupply of sun and uphill climbs. But at its core are the common factors that make all distance runs appealing to those taking part and largely incomprehensible to those who aren’t.

The intermittent pleasure gained from the pure act of running. The nauseating discomfort caused by pushing the body to its limit. The satisfaction of repelling the desire to stop. There is not much that is rational about an experience like this. The only time it really makes sense is when you are deep within it. I hit my 30km target and feel guilty as I leave the other runners to push on. When I talk to them at the finish line they are consumed by an experience that has been both endured and enjoyed. Next time I run it will be to the finish line and in conditions that could be even tougher than this.

Union Glacier base camp is our home for the Antarctic marathon. Initial impressions are that the temperature is manageable and it is a land where the sun always shines. As the camp staff explain to us though, planes can only land at the nearby ice runway when the weather is good so such a prognosis can be misleading. And so it was to prove. In the hours that follow, the temperature drops and the clouds roll in. My tent-mate’s head actually freezes to his sleeping bag during what was a fitful night of sleep for us all. But the weather is no barrier to the marathon getting underway as scheduled that morning. Months of imagining what this race would be like are over; reality is now well and truly biting.

Underfoot conditions are the immediate and persistent problem. One step lands in hard ice, the next in soft uneven snow. And then there is the issue of trying to see the step in front of you. The interior of my ski-goggles freeze to the point where the outside world is reduced to a desaturated smudge. But to take them off is to risk snow blindness, which effectively means you have sunburnt your eyes. The runner who finishes second will suffer from just that. In the days after the race his reddened, streaming eyes resemble those of a One Direction fan who has just been told Shane MacGowan will be playing the role of Harry Styles in all forthcoming videos. The other obvious discipline is to keep your fingers covered. This is not quite as easy as you would think when your hands start to warm up and sweat. A runner from Brazil decides to go mitt free for the final few kilometres. As a consequence, he has to undergo emergency treatment for frostbite at the finish and spends the rest of the trip with both his hands fully bandaged. We are all to learn that trying to eat dinner with mummified digits is neither easy nor particularly dignified.

As for my own run, it goes about as well as I could hope. The extra effort involved in keeping my footing does cause most of my leg muscles to fail at certain points. It is not pretty, stylish or quick but after more than six hours of forward motion the finish line does eventually agree to co-operate with my efforts. Trying to articulate my feelings into the Al Jazeera microphone at the finish is almost as difficult. Attempting to filtrate months of training and varied experiences into a coherent and worthwhile reaction is not easy. Relief and a degree of satisfaction are the immediate senses. But as time goes on, a degree of restlessness sets in as well. Could I have trained harder or perhaps smarter in order to better adapt my running to the snow? How much faster would I be in a regular road marathon? I had thought this escapade would be the final stop in my life as a semi-serious runner. But as many have found before me, finishing one race is never the end. It is just a detour on the way to the next one.

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