'I wouldn't have done it if I'd still been bellringing,' said my mother. Pulling the fitted sheet over the mattress on the top bunk bed (for visiting great-grandchildren) she'd pulled a muscle in her shoulder. At 89 it takes a long time for aches to go away.

Anyone else would have thought it was time to find someone else to make up the bunk beds for her, to say she was too old for such activities any more. Not my mum. She blamed the injury on the interruption to her regular three-times-a-week ringing of the church bells. She maintains this was keeping her upper-body muscles in trim.

But now the bells have gone away to be recast and rehung and she's missing the regular exercise. Her muscles are no longer as toned as they once were.

The older you get the more you realise the importance of taking exercise. Regular exercise, they tell you, keeps the weight - and blood pressure - down and the mind alert, prevents depression, wards off heart disease, strokes and cancer; it's better than any medicine.

I know that myself from experience. I make myself go for a walk every day; a minimum couple of miles no matter what the weather, and know I feel better for it. On the few days when I can't manage it I feel tense and restless.

But I'm conscious that although it's good exercise for the leg muscles, it doesn't keep the upper body in trim. As you get older, bits of you start to make themselves felt more than you'd like, especially when you need to make use of them. You find that opening pickle jars or marmalade pots is harder than it used to be. You feel unutterably feeble when you need help to lift the garden furniture out of the way so you can mow the lawn.

Some people tone up their arms and shoulders with weight training, but that doesn't appeal to me. The reason why I like walking is that it's not just exercise. You see the countryside around you, the changing seasons, flowers and birds; or if you're in a town, all the odd little things that go on in busy streets.

Slogging grimly away in a gym, exercise for its own sake with no distractions - no, that has no appeal for me at all. That's why my occasional resolutions about lying down on the floor every day to do those tummy-firming exercises tend to fizzle out after a few goes.

But my mother's remark has given me pause for thought. She's been bellringing for years, two hours of practice every Friday night, two sessions on Sunday, and the occasional ringers' outing to other churches to ring their bells and demolish a fine spread laid on by the host bellringers. And it all helps the tummy muscles (well, maybe not those ringers' teas) the arms and shoulder muscles, all the upper body.

Along with which, you make lots of friends and develop a good sense of rhythm, a sense of being part of a team. Now and then, ringing for a wedding, there's a bit of pocket money in it too.

You don't find all that in the gym. So maybe when those church bells are rehung I'll go along and join my mother and her friends in the ringing chamber. Then I'll not only get fit, with muscles as toned as any regular weight-trainer, but I'll have added a whole new dimension to my life. It makes sense doesn't it?