Anne Patel is 23 and lives in London. Like many Londoners she belongs to a gym; like many Londoners she rarely goes. "I just don't have time to," she says. "I've only been about seven times since September, but of course I've still had to pay the fee. So my last visit has cost me about £74, which is probably not the most cost-effective way of exercising."
Anne's experience is by no means unique. Gym membership has ballooned in Britainin 2000 Britons spent about £1.25bn on visiting gyms and fitness clubs. But given that Britain has ballooned as well, it doesn't seem to be having the desired effect.
"Part of the reason I don't go is because I'm busy," says Anne. "But I'd be lying if I said that was the only reason. Really I don't go because I'm utterly unmotivated. I find gyms so boring, and I find them lonely. But then I find the idea of going with a friend and standing next to each other sweating quite a revolting prospect too."
Another factor putting many people off is other gym members. A survey carried out a few years ago found that 20 per cent of those who didn't belong to gyms did not go because they were frightened of the sort of people who do go. These temples to the body seem to appeal only to the converted: to the uninitiated their rituals can seem confusing and the other worshippers can be intimidating.
"For many people, the mere idea of going to the gym is completely unappealing," says Dr Toni Steer of MRC Human Nutrition Research in Cambridge. "You can feel very self-conscious if you go into one and you're not really sure what you're supposed to be doing. And if you're overweight you might worry that you'll be surrounded by people with perfect bodies, which can be quite off-putting."
And ironically, one reason for not going more is guilt at not going enough. "The competitive aspect puts me right off," confirms Anne. "There is this sense that 'I went to the gym while you were at home watching Diagnosis Murder, ergo I am a better person and deserve a halo'."
Indeed, inactivity has had strong overtones of moral turpitude since the seven deadly sins were formalised in the 6th century. Although sloth didn't make it into Pope Gregory's original list, it soon found its way to number six. But there was a time when gluttony and sloth were in fact very useful characteristics to have.
"Idleness and greed are survival traits," says Andrew Prentice, Professor of International Nutrition at the London School of Hygiene and Tropical Medicine. "The human race has passed through many, many severe famines throughout its history. Starvation has been a major factor on human selection. The human is therefore programmed to lay down as much fat as possible. Greed helps you to lay it down, laziness to keep it there."
But these once-beneficial qualities are now doing more harm than good. The obesity rate in England has tripled over the last 20 years and is still rising. Around £200m a year is spent by the NHS on obesity-related health problems, and it is thought that it costs the economy £2bn a year. It is estimated that 70 per cent of men and 63 per cent of women in the UK are overweight or obese. The Government has recently launched a poster campaign on buses to encourage people to slim down. One such poster shows the back of an obese man next to the slogan "Don't look like the back end of a bus".
But the benefits of exercise go far beyond a trim rear. Research shows that active people have a 50 per cent lower risk of heart disease, up to 50 per cent reduced chance of developing bowel cancer and 30 per cent reduced risk of breast cancer.
And it benefits the spirit too. One in five people in the UK is thought to suffer from depression at some time in their lives. But exercise can help to alleviate the condition. A study carried out in America tested the effect that exercise had on elderly patients with major depressive disorders. One group was given antidepressants, a second took 30 minutes of aerobic exercise such as cycling, walking or jogging three times a week.
The results were dramatic: although the patients taking antidepressants initially showed a faster improvement, at the end of the 16-week trial the researchers found that "exercise was as effective [as drugs] in reducing depression among patients".
However, in the modern world opportunities for inactivity are numerous, and go far beyond the obvious one of the car. "These days we have escalators, lifts, automatic doors, cordless phones so we don't even have to stand up to answer the phone, and remote controls..." says Dr Steer. "The list is endless. While each of them only saves a small amount of energy, if you take them in their entirety it's quite easy to see how sedentary we are and how easy it is to be very inactive."
But if you repent of this lifestyle you don't have to do so by torturing yourself with a sporting penance. "People sometimes get this idea that the only form of physical activity is the sort of extreme thing you do when you go to the gym," says Dr Steer. "But it could take the form of doing the gardening, or the housework, or walking to the shops. It doesn't have to be serious sport to make a difference."
Paul Streets, Chief Executive of the Health Development agency agrees. "Many people waste energy feeling guilty for not going to the gym, when instead they should think about what activity they can do easily and do it," he says. "Leave the car at home for short journeys and walk instead."
Research has shown that exercise, such as walking, which is undertaken in a natural environment is more beneficial than that undertaken in an artificial one. Scientists in Tokyo studied the habits and surroundings of a group of octogenarians in Tokyo for five years. Their results showed that there was a strong positive correlation between taking exercise in parks and living longer. And of course it is much more pleasant. "It's just nice doing exercise outside, in the sun and the fresh air," says Anne. "I enjoy doing it - and as a result I do do it."
Not using energy-saving gadgets can also have a cumulatively beneficial effect. "If you make a decision that you will take the stairs, and you will get up to answer the phone, then those sorts of small changes over the long term can really make a big difference," says Dr Steer. For example, if you work on the second floor of an office, and take the stairs instead of the lift, in two months you will have climbed the equivalent of Ben Nevis. And 30 minutes of housework a day will also give you a quick workout.
So although doing the housework sounds a dowdy way of getting yourself and your rear in shape, it is nevertheless effective - and cheap. And its reputation is on the up. In this month's Elle, Kylie confesses to being a fan herself. "I do like a good clean," she says. "I'll get my Marigolds on and have a fantastic frenzy." And everybody knows there's nothing wrong with her bottom.
EASY WAYS TO EXERCISE
* The drop-out rate among new gym members is up to 80 per cent in the first eight weeks
* The biggest positive change you can make to your exercise levels is in how you get about. Choose the stairs over the lift, walking or cycling over driving
* Studies have shown that an accumulation of slow-burn activities expends more energy than short bursts of exercise such as that taken at the gym
* To qualify as "active" an adult has to take part in some form of physical activity for 30 minutes, five days a week
* Gardening can burn up to 350 calories per hour and housework 144. Climbing four flights of stairs takes seconds, yet uses up 11 calories
* A one-mile walk to the local shops and back will use up more than 300 calories, so forget internet shoppingReuse content