I am always surprised when things break down. Take the car (now that it's worth less than a tenner, I leave it unlocked in hopes that someone will). It makes strange noises. Sometimes it doesn't start. Sometimes it doesn't stop. My first reaction is to call the garage, but my second is to quash such negative thinking. Why worry when nothing is really wrong? Needless to say, this means I am the RAC's best customer. Last time, even the call-out man seemed to think I should have seen it coming. Doesn't he realise it's people like me that keep him in work?

But while the car may collapse, the gas fire splutter and the immersion heater grow cold, I'm not nearly so blase about the human body. I have known the truth about ageing since I was 10 and spent the year watching my teacher Mrs Grant's upper arm wobble like an unfrozen cold pack whenever she wrote on the blackboard (which was frequently). My next teacher had a expanding set of gyrating chins. The lesson was clear: if you aren't careful, the wobble will get you too.

So I am in favour of anything that keeps the decay at bay. and can only welcome Asda's new "Shape Up and Shop" programme.

"Mr Motivator Gets Asda Shoppers in Shape", says the press release. (I had thought Mr Motivator was a kind of toilet cleaner, but now know that he is a health and fitness expert on daytime television.) He has devised a handful or so of exercises, including one called the Asda Walk.

"Great for toning the buttock muscles," the pamphlet says. "As you push your trolley along, stay as close to it as possible. Keep your upper body upright, and keep your stomach tight at all times. Chest up! Shoulders back! As you walk, squeeze your buttocks together, then release. Repeat often as you walk up and down the aisles."

There is also the Fruit Bender, the Shelf Crouch, the Top Shelf Peek, and one that involves hoisting large amounts of drink around. And who could resist Hot Stuff?

"Hold on to the side of one of the freezers with one hand and gently run on the spot. After a few minutes, change the routine so that your heels kick your buttocks ... Repeat until you start to feel really hot!"

The whole thing takes place in the Watford store tomorrow at 11am. I can hardly wait. The car, however, is making a worrying noise, and for once, I'm trying to get it fixed before it breaks down. Who can be wobbly when Mr Motivator's in town?