Physical exercise is important for maintaining physical fitness and can contribute positively to maintaining a healthy weight, building and maintaining healthy bone density, muscle strength, and joint mobility, promoting physiological well-being, reducing surgical risks, and strengthening the immune system. Exercise reduces levels of cortisol, which causes many health problems, both physical and mental.
Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons including strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance, as well as for the purpose of enjoyment. Frequent and regular physical exercise boosts the immune system, and helps prevent the "diseases of affluence" such as heart disease, cardiovascular disease, Type 2 diabetes and obesity. It also improves mental health, helps prevent depression, and helps to promote or maintain positive self-esteem. Health care providers often call exercise the "miracle" or "wonder drug” providing a wide variety of proven benefits that it provides.
Frequent and regular aerobic exercise has been shown to help prevent or treat serious and life-threatening chronic conditions such as high blood pressure, obesity, heart disease, Type 2 diabetes, insomnia, and depression. Endurance exercise before meals lowers blood glucose more than the same exercise after meals. According to the World Health Organization, lack of physical activity contributes to, heart disease, diabetes, falls in the elderly, breast cancer and colon cancer.
There is some evidence that vigorous exercise is more beneficial than moderate exercise. Some studies have shown that vigorous exercise executed by healthy individuals can increase endorphins, increase testosterone and growth hormone, effects that are not as fully realized with moderate exercise.