I was 18 years old, fit, strong and ambitious. I played rugby and squash, and wanted to be a professional golfer. I was really competitive; I still am. One day on the squash court, I fell down for no apparent reason. I jumped up and got on with the game, but soon after I noticed a deterioration in my health. I saw multiple specialists and eventually, after two years, I was diagnosed with limb girdle muscular dystrophy (MD).

I call it my Cast Away moment, after the Tom Hanks film. It was a very difficult time. I had no idea what life was going to throw at me and I was scared. It turned out my mum was a carrier of the mutant gene, the genetic cause of the condition. I made her life hell for a couple of years and blamed her for everything. I obviously regret that now, but I was incredibly angry.

It depends on the type you’ve got, but MD is generally progressive, deteriorative and relentless. By my late 30s it was already quite advanced and I had transitioned from a walking stick to a manual wheelchair and then my power chair, which I call my chariot. I wanted to be master of my own destiny, so I had to recognise my strengths and play to my weaknesses. The way I’m wired is to set the task and say, “We’re going to make this happen”, and what I wanted to make happen was a trip to the north pole.

People with MD feel the cold, particularly in their extremities. So why did I want to go to one of the most extreme, cold and inaccessible places on Earth? I’d read about Chris Cope, who wanted to go to the north pole to raise money for MD, and it had appealed to my adventurous spirit: I wanted to raise awareness about the condition, but I also wanted to find out what I was capable of. I’m very competitive.

I was still able to walk a little in 2002, though very slowly. I couldn’t feel my legs or my toes, but what I feared most was failing, so I had lots of life coaching and did some cold training in Norfolk, in a huge deep-freeze unit (the size of several aircraft hangars, filled with frozen peas). It helped me to assess how my body would behave in extreme cold. It wasn’t pleasant but at least I knew what to expect.

I had an amazing team around me, including a major from the Royal Artillery; but the four different flights we had to take to get to the inner Arctic ice shelf were nevertheless daunting. Finally a Russian plane took us to the Arctic ice cap. While we were on the ice the runway split and we had to wait 36 hours for it to refreeze. I was on the ice for the best part of three long days. There was much joy, punching of the air and tears once we reached the north pole.

It was while we were there that we agreed to tackle the south pole, too. It was certainly a high-risk undertaking, but I set up the Muscle Help Foundation the following year, and in 2004 we went to the south pole. In the two years it had taken to organise the expedition, my muscles had deteriorated further and I had started to lose my ability to walk. I suspect the expedition to the north pole was partially responsible, but we pressed on regardless.

We flew to a base camp on the inner Antarctic ice shelf to acclimatise for a week. Then we flew another two and a half hours closer to the pole. I spent 15 days in Antarctica; I travelled the last 5km flat on my back, strapped in an adapted sledge, then walked the final 350m. The expedition raised £50,000 for charity.

I remember arriving in the south pole with a pounding headache because we were 2,700m above sea level. I was bitterly cold, exhausted and a complete mess. I phoned my wife in England and couldn’t speak for the first two minutes because I had completely lost it. Eventually I managed to utter the words, “Babe, I’m here.” I was shredded physically, mentally and emotionally. It almost killed me.

Muscular dystrophy is slowly destroying my life but I have chosen to fill it with experiences. I’m on this mission and I live life to the full. For me, it is absolutely no dress rehearsal.

• As told to Bill Borrows

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