Two years ago, I could not run for a bus without feeling as if my lungs were on…

Two years ago, I could not run for a bus without feeling as if my lungs were on fire. Last Sunday, I finished my first marathon in four hours and fifty-two minutes. I was not fast, but I did not stop once.

It all started with a bet. At a friend's birthday party, someone joked that none of us would ever run more than five kilometres. I said I would run a marathon within two years, mostly to win the argument. The next morning, I realised that I had no idea how to start.

I downloaded a free beginner's programme that mixed walking and running. In the first week, I ran for one minute, walked for ninety seconds, and repeated this eight times. It sounds easy, but I was exhausted. Slowly, the running parts grew longer and the walking parts shorter. After nine weeks, I could run five kilometres without stopping, and I was more proud of that than of almost anything I had done before.

The hardest part was not physical. It was getting out of bed on cold, dark mornings. What helped most was joining a running club. Knowing that eight people were waiting for me at the park at seven o'clock made it impossible to stay under the duvet. The club also taught me things I would never have learned alone, such as how important it is to run slowly most of the time, and how to eat properly before a long race.

I also learned to listen to my body. Six months before the marathon, I hurt my knee because I increased my distance too quickly. I had to rest for three weeks, which was terribly frustrating, but a physiotherapist showed me exercises that made my legs stronger, and I have not been injured since.

The last ten kilometres of the race were the most painful thing I have ever done. But when I crossed the finish line and saw my friends cheering, every early morning felt worthwhile. And yes, I won the bet. The prize was a pizza, which I ate in about four minutes.