Victor Meldrew, the elderly central character of the British sitcom One Foot in the Grave, finds modern life almost impossible to figure out, as indicated by his catchphrase "I don't believe it!" But among the most memorable of his one-liners are the words he utters moments after the teacher of his new evening course collapses and dies, mid-sentence, in front of her students. "She can't be dead!" he insists, as his classmates panic around him. "She's a health and fitness instructor!"

Laughter apart, most of us will understand his confusion. In recent years, health and fitness have become an industry in themselves - and one with its own mystique. During the years of the economic boom, it seemed that health food shops and gyms were opening on every main street where prosperity reigned. No tourism or leisure experience was complete without the presence of a spa offering the latest health treatments, from hot stone massages to seaweed therapy. Scientific medicine found itself competing with natural or traditional alternatives, from aromatherapy to homeopathy. It was tempting and easy to believe that these health and safety practitioners possessed the secret of a long life, free of illness - or, at least, that they had no business succumbing to the Grim Reaper before the rest of us.

And if their therapies worked few miracles, they tended to do no harm. But as it turns out, staying healthy and fit is easier, and cheaper, than it often appears. The basic advice is the same, whether it comes from television health pundits or those who brought us up. If we want to remain fit and healthy for as long as possible, we need to eat more fruit, vegetables and protein than sweets, crisps and fast food. We should also drink less alcohol, avoid drugs, and take regular exercise - which can come from a daily walk or cycle, as well as the gym. We need to build up a regular sleep cycle, and make breakfast the most important meal of the day rather than an afterthought on the way to work.

All this advice sums up things people have done for centuries, before life was made easier and yet less healthy by fast food, fast cars and the growing tendency to watch sport on a screen from the comfort of the sofa rather than go outside and chance your four limbs at playing it. Not even health and fitness instructors can avoid the Grim Reaper, as Victor Meldrew found out. But staying fit and healthy can make life a happy and satisfying experience for everyone.