Think about it. A 30-minute walk every day can probably do more for your health than all the efforts of a dozen doctors and ten different types of medication.

We have scrutinized the medical journals. Here's a summary of the proven health benefits of exercise:

1. It's good for your heart
"Even a moderate amount of exercise helps your heart," says Dr William Kraus, associate professor of medicine at Duke University Medical Centre in an article published in The New England Journal of Medicine. "Some exercise is better than none and more is better than less."
Exercise reduces LDL cholesterol, the kind that clogs arteries. It also reduces your blood pressure, relieving stress on your heart; improves your insulin sensitivity; improves heart muscle function and blood flow and diminishes the chances of developing blood clots. These findings have been corroborated by a host of studies over the years.

2. Exercise promotes weight loss
Research has shown that to have an effect on weight loss you need to exercise for at least 30 minutes a day. You can also do an hour of intensive exercise every second day if this fits into your schedule more easily. Be consistent and be regular. Do those one-hour exercise sessions three to four times every week, not just one week a month, and you will achieve the result you desire - to lose weight and keep it off, says Dr Ingrid van Heerden, registered dietician.

3. Exercise is an excellent de-stressor                                                              It's general knowledge: exercise counters stress and depression. But exactly how and why does this work? Exercise acts as a temporary diversion to daily stresses and it improves self-esteem. Increased core temperature during exercise may lead to reduced muscle tension and favourable alterations in brain neurotransmitters. Mood improvements may also occur due to the increased secretion of endogenous (internal) opiates, e.g. endorphins. Psychological changes may occur because of changes in norepinephrine, dopamine and serotonin, all hormones which can affect mood and anxiety levels.

4. Exercise prevents colds

One doesn't automatically associate regular exercise with a reduction in the number of colds people get. But researchers from the University of Carolina found that people who exercised regularly were 23% less likely to get colds than those who exercised less. And if those who exercised got colds, the symptoms disappeared more quickly than in the study participants who did little exercise.

5. Exercise reduces diabetic complications
Lifestyle factors have a huge impact on certain conditions - and diabetes is one of them. Exercise can help to reduce your insulin requirements, lower your cholesterol levels and high blood pressure, and in the long term can reduce the development of heart disease and stroke. This is important because diabetics have a higher risk of developing heart and circulatory problems. Exercise can also promote weight loss, improve circulation and reduce stress levels (raising your glucose level). Health experts believe that exercise spikes the immune system for a few hours each day, helping to ward off colds. Thirty minutes of brisk walking is enough to make you reap the benefits of exercise.

6. Exercise improves oxygen and nutrient supply to all cells in your body.

An American study indicates that '80-plus-ers' can dramatically improve their health by exercising a few times a week. If this is true for elderly people, it certainly is for the younger set as well. Exercise apparently not only improves the body's utilisation of oxygen, but also lowers systolic blood pressure (high pressure is a dangerous condition common in elderly people). Positive results were obtained from the 22 elderly people (80 years and older) who took part in the study at the Veterans Affairs Ann Arbor Healthcare System in Michigan.

7. Exercise combats impotence

If you stop and think about it, it makes sense - increased circulation as a result of exercise should result in lower levels of impotence, as getting an erection is dependent on the efficiency of blood circulating to the penis.

"Losing weight, stopping smoking and doing more exercise are associated with better sexual health," says Dr Andrew McCullough, director of Male Sexual Health, Fertility and Microsurgery at New York University Medical Center in New York City. "We talk so much about treating, treating, treating. Here we're beginning to see an increasing body of evidence that we can modify the appearance of this by changing lifestyle."