I'm sure that you, like me, keep mental lists of things that you intend never to do in your lifetime ­ Unbreakable Life Maxims. They are a mixture of sensible tips ­ ULM 1: "I will never play Russian roulette" ­ and personal prejudices ­ ULM 7: "I will never play anything by Santana". Always fairly high on my list has been an aversion to exercise, and particularly to gyms ­ ULM 3: "I will never, ever, set foot in a gym". Except for a few embarrassments with bars and ropes at school, it was a rule I'd managed to adhere to. Until now.

I'm sure that you, like me, keep mental lists of things that you intend never to do in your lifetime ­ Unbreakable Life Maxims. They are a mixture of sensible tips ­ ULM 1: "I will never play Russian roulette" ­ and personal prejudices ­ ULM 7: "I will never play anything by Santana". Always fairly high on my list has been an aversion to exercise, and particularly to gyms ­ ULM 3: "I will never, ever, set foot in a gym". Except for a few embarrassments with bars and ropes at school, it was a rule I'd managed to adhere to. Until now.

Perhaps the defining moment in this aversion was exposure, while in my formative teenage years, to university flatmates caught up in the risible fashion for leg-warmers, possessing copies of Jane Fonda workout tapes and addicted to awful movies such as Dirty Dancing and, most horribly, Perfect, in which Jamie Lee Curtis discovers the joys of the rowing machine. I was scarred for life. For me, then, one of the most unpleasant conclusions of my multiple sclerosis diagnosis came not from the neurologist, but from the physiotherapist. "It's important to build up the muscle in your arms and legs. Lots of exercise. Are you a member of a gym?"

The Essex Health Club is situated on a Second World War airfield. One's first impressions are that the Germans did a pretty accurate job of targeting the site, leaving hideous craters everywhere. Sadly, no: that's the golf course. And that architectural bad dream in the middle of the car park must be the gym.

The car park is heaving, but with my new disabled parking badge, I can manoeuvre right next to the chalet. This blue badge is enormous, reminiscent of those charity cheques that businessmen hand over on Comic Relief night. But the badge has the desired effect of stopping the bolshie parking attendant in his tracks, before he can send me to a vacant slot three miles away. He slinks away, cursing.

I walk into the club and stumble past piles of golf trousers, balls and even left-hand-only gloves for sale. Into the gym. Bye-bye, Unbreakable Life Maxim 3. First, dispel any notions picked from Jamie Lee Curtis that gyms might be sexy. The acres of sweat and flab on display are anything but. In fact, the bethonged women look less reminiscent of Jamie Lee after a shower than of her mother, Janet Psycho Leigh, in the shower of the Bates motel after Norman has had his fun with a knife.

To avoid a sudden MS attack, it is necessary not to raise my temperature unduly. As a result, my circuit at the gym is embarrassingly easy: no more than four minutes on any piece of kit. Hence, while the other members of the Essex Club spend hours in skimpy shorts and T-shirts drenched with sweat, I'm able to do my entire routine without taking my jersey off. Not only that, old ladies gasp in horror when, after they've spent 20 minutes pumping 150lbs on the rowing machine, I saunter over and reduce the weight to 70lbs for my two minutes. Nevertheless, after a couple of minutes on the treadmill my temperature has risen enough to ensure that I'm staggering around like a drunkard, my vision and balance gone.

Actually, the effect on my vision is not entirely unwelcome, since the view out of the club window is particularly depressing: one half-filled skip and a putting green covered with hundreds of men mis-hitting balls. Never having played golf myself, it looks all too easy to get the ball in the hole from five feet, which makes it toe-curlingly irritating to watch people fail time and again. If something is that hard, it can't be worth doing, let alone paying for.

Turning my attention away from the window, I am faced by a bank of telly screens. Now, being something of a television addict, you might think I'd welcome the opportunity of some quality time with the box. And, indeed, I did time my weekly excursions to the club to coincide with David Frost's Sunday chats on the sofa. However, the club's management seems to have decided that although you may watch TV while pumping iron, you may not hear it. So I am left with the sight of Frostie and guests goldfishing about the events of the week. But all I can hear is ... what is that din?

Back in the 1970s, Brian Eno released a series of muzak albums ­ Music For Airports, Music For Lifts, Music For Films etc. But he omitted Music For Health Clubs. That vacuum has now been filled, alas, ("Cause I am your laydeeeee") by compilation tapes of 1980s power anthems ("Who's gonna drive you hoooooome tonight?") played at top volume ("Take my breath awaaaaay"). Nigel from Spinal Tap would surely approve of these speakers, which seem stuck on 11 ("Everything I do, I do it fooooooor you"). At least, I suppose that they have the desired effect since the crashing guitar sounds ensure that everyone cracks on with their pec-enhancement regime and gets out of the gym as soon as possible. But not before checking to see if they have moved up the ladders which adorn the walls, one marking VO2 scores ­ whatever they are ­ and the other showing the frequency of attendance. Unlikely ever to feature in either of these competitions, I am free to marvel at the dedication ­ insanity? ­ of those vying for the top spot, who hit the treadmill about 28 times a month.

My routine complete, it's time to go. Time, too, to come up with a new Unbreakable Life Maxim 3. How about "I will never buy Ian Lang's autobiography". Pretty safe, you might think. Until you discover that I've got two copies of Norman Fowler's.