The marathon is still more than three weeks away but already I'm thinking about the afterglow, the pleasant feeling of satisfaction I have been promised once it's all over. Perhaps it will be the warm heavy clunk of a cheese sandwich as it lodges itself in my stomach, the icy fingertip chill of the cold beer in my hand and the thought of not a single race to be run for the rest of my life. No more nights of anguish, cancelled pub appointments, staying late at work to avoid the run I know I need to do. And then there's the sense of achievement ...

But before that there is more pain. Having briefly drifted on a legal high following my sound trouncing of Britain's most successful athlete (Sir Steven Redgrave) in the Murcia half marathon last week, I have come down to earth. I am back on the treadmill, the only memory of my victory, a fading photo in my shorts pocket.

Meanwhile I have been bombarded with reports on what I should be doing to make my body more of a temple, less of a takeaway. This ranges from what shoes I should be using for my training to what shampoo will make my hair right for running. I've also been told my favourite isotonic drink will not be available on the day. Instead there will be a rival brand handed out every five miles. Apparently I need to try this out before the big day, otherwise I could be sick.

But it isn't all bad news. I have discovered a free way of relieving my body of bruises, aches and pains: the cold bath. After a long run, slip into the invigorating comfort of a completely chilled bath for 15 minutes. If you can manage not to grind your teeth into paste, good things will happen to your body.

I am told the logic is this: when you run you get hot and blood rises to the skin surface in order to cool you down. That's why we all go red when exercising. But after a long run you need your blood to be in your muscles, breaking down lactic acid build-ups and helping to mend those minor tears. So to drive the blood there ultra quick and ensure it gets to work, immerse yourself in a cold bath. Blood is no longer needed on the surface and retreats. Another top tip. Who said running wasn't fun?