Clunk. "Ow!" Clunk. "Ow!" That is the sound of my own hand jerking involuntarily and hitting the table with a thump. I am wearing the Slendertone arm toner, two black belts strapped around my upper arms, and every few seconds a pulse of electricity is sent through the pads, contracting the muscles. It works on much the same principle as those machines they use to revive people in hospital, though these have been developed to eliminate flabby arms and not, you know, death. Except, I'm sorry but I just can't take it. It's deeply disconcerting to have your limbs jumping beyond your control. I give up.

The waist toner, however, is a different matter. This could be the exercise regime I have been waiting for - I do nothing that could be accurately described as "exercise". I'm not in bad shape, though I could do with toning up, so Slendertone should be perfect for me. I can lie on the sofa and watch EastEnders while the tummy belt works my abs. I strap it on, placing the sticky pads in position on my stomach. That's all I need to do, half an hour for five days a week for a month.

Believing I would end up with a stomach like Geri Halliwell's without having to do a single sit-up left me with a warm fuzzy feeling, though that could have been the voltage coursing around my stomach. Theoretically, you can wear it anywhere (I wore it to the supermarket, with the control unit tucked down the back of my pants; while doing the washing up; at my desk).

Has it worked? I haven't lost noticeable inches, though my stomach feels firmer. But the change isn't drastic enough to make me rave about this contraption and, more than that, it made me feel like a cheat. What began as its biggest attraction - being able to lie around watching TV while "exercising" - became a source of shame. Even if it had given me the muscles of Kelly Holmes, I wouldn't have felt I had earned it, there would have been no sense of achievement. Incredibly, the Slendertone has changed my whole attitude to exercise - I've just joined a gym.