I was never really one for exercise. I hated the experience of PE at school – playing sports I was no good at, getting dirty and sweaty for no good reason, the perceived humiliation of the changing rooms and showers. My school had a strong rugby focus; my focus was avoiding the ball at all costs. In football, I remember being in goal and a team member passing the ball back to me. Somebody shouted “don't pick it up” – so I let it pass between my legs and into the goal. The teachers could never engage with those of us who weren't that interested.

I didn't mind basketball so much – it was indoors for a start, and I wasn't terrible at it. Hockey was bearable as well. But as soon as I could drop PE from my curriculum, I did. I never understood the mentality of those who enjoyed sports and exercise, and to be honest I still don't.

Nonetheless, I can't escape it. Modern life is pretty sedentary, and being a computer geek, mine particularly so. I sit in front of a computer between the hours of 9 and 5 – and very often do much the same when I get home from work. A walk to the shops every couple of days isn't going to cut it. Over the last five years or so I've been getting gradually larger. And larger.

Yesterday, I rejoined the gym. They are strange places, artifices of sweat and hope and air conditioning. Rows of treadmills and cycling machines and other contrivances, all facing a bank of television screens showing news, music and daytime TV. In the two years since I was last a member, all the machines have been replaced – and I suspect that Virgin Active have a rolling programme of renewal and replacement so that they can resell themselves as new on a regular basis. Gyms are not social spaces, with most of us plugged into iPods, the rows of machines all facing the same way. Perhaps we're not really a social species any more.

I dread to think what the environmental impact of a modern gym is. We plug ourselves into electric devices to replicate the experience of running. Huge air conditioning systems keep us cool in a room with no windows. The gym is open from 6.30am to 10pm, lights blazing the whole time. The pool is maintained at a constant temperature. There's a bank of computers. The list goes on. I think I'll do some research on the average gym's CO2 emissions – not that it will stop me going.

So I have committed myself to a year's membership, and I have been twice this week. According to the Wii Fit, I've lost 1lb in that time. Only 3 more stones to go. I think a post on Food may follow. And then Drink.