I must be crazy, but I am training for my third marathon. Yes, 26.2 miles of sore feet, painful knees, chaffed inner thighs - in short, complete hell. So why am I doing it?

I ran my first marathon three years ago - the great London Marathon. I thought there would be no better way to start off what will inevitably become a life-long obsession by going in with the big guns straight off. From what I can remember - like childbirth, the pain disappears with that strong scent of nostalgia - it was one of the most amazing days in my life, crying from happiness from beginning to end for the whole 5 hours and 22 minutes.

In reality I was crying from the agony, but so what? I got a cool medal and lots of attention - what more could you desire? I even grabbed the chance of having a smoke in front of my mum at the finish line knowing that there was no way she would bollock me. Plus the joy of guilt-free gorging on a family size packet of Hula Hoops and king-size Snickers. It was a truly revelationary experience.

So now I am trying to show off and have committed myself to do the Berlin marathon for the NSPCC. My training runs are getting longer - I am now up to 13 miles - and I've developed a sweet tooth that would put a stoner trapped in a sweet shop to shame. And you know what? I am absolutely knackered. Piggyback anyone?

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