"You need a specific goal, whether it's to lose weight for a special occasion, or to improve the strength of your abdominal muscles," advises physiotherapist Catherine Chambers.

"You also need to have an attainable exercise programme that starts slowly and increases in intensity as your fitness improves. I suggest you get expert assistance from a physiotherapist, a biokineticist or a personal trainer, who can help you plan a programme tailor-made for you."

The plan needs to take into consideration any pre-existing injuries or health problems, as well as how fit you are. You also have to be sure that you're working all your muscles, especially the important stabilisers that support your skeleton.

"What most people do when they start a home exercise programme is hop on the stationary bicycle and pedal furiously," says Chambers. "But although that would improve your cardiovascular fitness, it is not all you need to do. I suggest you start with exercises to strengthen the stabilisers, as they have a protective function that will help prevent injury, then work to improve your postural alignment. The Pilates system is one example of how you can work these muscles, but any exercise expert will be able to design suitable exercises for you. This inner core is crucial to a balanced exercise plan."

The bare minimum
Being sedentary makes you weak and more prone to injure yourself doing something silly like lifting a heavy suitcase. Most experts agree that even a little exercise is better than none. Ten minutes of walking up and down the stairs will make you feel more energetic and stronger.

"If you're weeding the garden or painting the garage, you're using your muscles and you can count that towards your day's minimum quota of exercise," says biokineticist Lisa Micklesfield, who manages the Healthy Weight programme at the Sports Science Institute in Cape Town.

"There's a difference between exercise for health and exercise for fitness. For health, the American College of Sports Medicine recommends that you accumulate about 30 minutes of exercise most days of the week. It doesn't have to be one session, but you do have to be working at a moderate-intensity exercise. You need to get your heart rate up slightly. This allocation won't necessarily get you fitter or improve your body shape, but it does have important health benefits."

If you're exercising to improve your fitness, you should aim to do cardiovascular exercise three to five times a week at a higher intensity (65 to 90% of maximum heart rate) and this will determine the duration, as the higher the intensity is, the shorter the duration will be. To determine your maximum heart rate, subtract your age from 220, then calculate 65-90% of this. This is a good general guide, though things such as medication can alter the rate.

A home exercise plan should include some stretching and some strength work so that you're lengthening and building your muscles in a balanced way. "You do need to do some resistance training," says Micklesfield. "but you don't need to buy fancy equipment; you can use baked bean cans or a Coke bottle filled with sand while you do upper-body work."

"If you have a plan worked out for you it will include a variety of exercises, but if you're following a book or video be aware of potential problem areas, especially if you have a previous injury. Wear whatever's comfortable and get the right shoes. Your body takes time to adapt, and you need to protect yourself from injury. Variety is the key and I believe that different things suit different people."