PERSONAL trainers used to be monopolised by Madonna, Sylvester Stallone and assorted celebrities hanging out in LA. But on Wednesday and Saturday mornings I go pounding the backstreets of Kensal Green with my own personal trainer. Glamorous it is not, but after years of intermittent attempts to get fit, I have decided the time has come for radical action.

Personal trainers are supposed to come to your place, but the thought of the neighbours catching sight of me doing star jumps in the street was too humiliating. So twice a week I drive to Kensal Green for hour-long sessions designed to turn me into the sort of guy who kicks sand in other guys' faces.

My personal trainer's name is Karin, but she prefers to be called Lady K. It seemed a short step, however, from such an appellation to Miss Whiplash and a world of whips and chains. So I called her Karin. And I asked her not to hurt me.

That first morning was an ordeal. As I rang the front door-bell, clad in saggy tracksuit bottoms and off-white T-shirt, I was convinced that net curtains were twitching all along the street. In fact, I need not have worried about the neighbours. Most of the activity that first time took place in the living-room, away from inquisitive eyes. I insisted that even the cats were shooed out before I so much as touched a dumb-bell.

My trainer has the sort of sleek, well- toned body that would put Jane Fonda to shame. She spends several hours every day keeping it in trim, and when she is not exercising her body, she is talking about exercising it. Frankly, she terrifies me.

That first time, I couldn't do anything right. My hands were placed all wrong for the three-quarter press-ups. I kept falling off balance for the lunges. My star jumps . . . well, the less said the better.

Personal trainers love jargon. They talk about tricep dips and prone flys and lower- back extensions. And they make a point of telling you which part of your musculature these activities are benefiting.

Karin puts me through a routine that combines these exercises with 20-second spells jogging on a piece of appara-called a rebounder, which is a mini-


The worst bit, however, is the psychological stuff. At the moments when I am seriously suffering, she comes on strong with all this encouraging guff. 'You're doing really well, Roger,' she says in such a transparently false and insincere manner that I want to throttle her.

Then she tries to get me to smile: 'Come on, cheer up. Don't look so grumpy.'

And so, feeling even more grumpy, I try to compose my features into something resembling a smile. My mind drifts back 20 years or so to PE lessons in the school gym. I hated them - the impossible demands, the bullying competitiveness, the physical discomfort - but never, never, did anyone order me to smile.

However, four weeks on from that trying first date with Lady K, I am fitter than I have been in years. And I have discovered that Karin is human after all: at weekends, she goes swimming with dolphins in the North Sea. Never mind my body, these visits to Kensal Green could change my life. Eat your heart out, Madonna.