I'VE become rather lazy about going to the gym lately and I'm trying to wean myself back into exercise with gentler forms of sport, so I thought I'd give yoga a go.

I had seen posters of Bikram yoga with bendy models holding dancerly stretches which looked quite attractive. I got a leaflet telling me it was done in a heated room. The idea behind the concentrated heat is that you are able to stretch and bend your muscles to a greater degree, without twisting something or doing your back in.

But for something that looked fairly sensible on paper, the reality could not have been more different when I went for my starter lesson. It all looked deceptively serene when I entered the room. Rows of people with excellent posture were standing in front of a mat and towel spread out before them. I was startled to see that many of the men had turned up in tiny Speedos and the women weren't wearing much more, looking as if they were getting ready for a beach repose, not a workout.

We started off with a few breathing exercises as the heaters began to whirr. There was some initial huffing and puffing as people near the heating vents began to feel the warm air. Pah! I thought. These people would keel over in one of my frenzied aerobics classes.

After holding a few stretches, I began to feel a little red faced and my damp sweat pants began to cling heavily me. Another few stretches later, my clothes felt like dead weights and the Speedos began to look more and more sensible. The greatest problem for me was doing the excruciating bends, curls and contortions as well as breathing.

Looking around, no-one else was struggling with the same dilemma. They all seemed to have the lung capacity of dolphins as they continued to breathe deeply and slowly, even with their legs wrapped around their waists. I had never before appreciated how aerobic it could be standing on one leg. The longer we held the pose, the more my heart pounded and it felt like I was on the 20th mile of a never-ending marathon.

Sucking in steam and hot air, I felt too choked to cry. Attempting to bond with a fellow failure while I wobbled and flailed, I saw that other people obviously meant business. They fell into athletic poses without a wince and held it for three minutes in monastic repose while I grunted and gurned at the mirror. We were finally allowed out of the torture sauna and I hobbled home with a thumping dehydrated head and aching limbs, having fantasies of setting my bed up in the freezer for the night. I couldn't even look forward to the prospect of a hot bath for fear of the steam.

I made resolute plans to head straight back for a 20-minute workout at the gym on Monday morning. At least the air conditioning would be on.