I’m writing this from Portugal, where I’m staying with my old friend Sean Langan. His family has owned a farm in the Algarve for several generations and I first came to stay with them when I was 18. I continued to spend every summer here for the next five years and, together, they represent some of the happiest periods of my life. This is the first time I’ve returned in a quarter of a century.

Wherever I go, the memories come flooding back. There’s the veranda where I sat with a bucket of warm water and a Bic disposable razor, shaving off the hairs that had appeared on my chest. There’s the car park where Sean and I raced around in our Mini Mokes, practising our handbrake turns. There’s the cave that I swam out to with Mandy, a freckle-cheeked brunette. We made out on a tiny stretch of sand, unseen by our friends on the beach.

I’d like to be able to say that I fell in love for the first time during this period, but the truth is my heart had already been broken by the time I arrived in Portugal. Those summers were an opportunity to rebuild my confidence — a kind of sexual therapy. There was one two-week period in particular in which I enjoyed a degree of success that I’d never experienced before. By the time I left, I felt as if I’d finally become a man.

It all revolved around a girl. Gaby was a 19-year-old German and so dazzlingly beautiful you couldn’t stare at her for more than a few seconds without having to look away. She had a 21-year-old German boyfriend — the sort of strapping, muscle-bound Teuton that made you wonder how we won the war — and, as far as anyone could tell, she only had eyes for him. Sean and I would sit in the beach bar, stealing glances at her, and raging at the injustice of a universe in which the two of us would never possess a girl like that.

Then, one afternoon, I swam about 200 yards out to sea and remained there, treading water, staring back at the beach. I looked at Gaby, lying with her head on her boyfriend’s stomach, and decided I didn’t have to accept the hand that fate had dealt me. I might be short and fat, but if I put my mind to it there was no reason I couldn’t steal her from under Fritz’s nose. I swam back to the beach, introduced myself to the German couple and spent the rest of the afternoon regaling them with funny stories. They both thought I was hilarious.

Turned out, Fritz wasn’t her boyfriend but her brother, and when Sean and I offered to take them on a tour of the local nightclubs they leapt at the chance. I can remember the song that was playing when I first took Gaby in my arms — ‘Don’t You (Forget About Me)’ by Simple Minds. A couple of nights later, as we lay beside each other on the beach, I remember feeling a tremendous sense of opportunity. If I could seduce a girl as beautiful as this, anything was possible.

Almost 30 years later, I swam out to the same spot and took stock of my life. This time, the woman I was staring at on the beach was my wife, along with our four children. I realised that if I hadn’t summoned the courage to talk to Gaby all those years ago, I wouldn’t have been bold enough to propose to Caroline, or embark on a career as a freelance journalist, or set up a school. It was a pivotal moment, the point at which I decided to become the author of my own destiny.

In some ways, it was an expression of appalling egotism. Why should a German goddess give herself to an Anglo-Saxon homunculus? It was the sort of arrogance that, in a Greek myth, would be punished by some terrible ordeal. Yet, at the same time, it’s a rush of blood to the head that I want my children, as well as every other child, to experience. If you’re going to become a fully realised human being, you have to experience a moment of defiant self-belief in which you convince yourself you can be the master of your fate, whatever the odds. I realised all those years ago that it is only by reaching for the impossible that you discover what’s possible