Physical exercise is the performance of some activity in order to develop or maintain physical fitness and overall health. It is often directed toward also honing athletic ability or skill. Frequent and regular physical exercise is an important component in the prevention of some of the diseases of affluence such as cancer, heart disease, cardiovascular disease, Type 2 diabetes, obesity and back pain.

Exercises are generally grouped into three types depending on the overall effect they have on the human body:

Flexibility exercises such as stretching improve the range of motion of muscles and joints.

Aerobic exercises such as walking and running focus on increasing cardiovascular endurance.

Anaerobic exercises such as weight training or sprinting increase short-term muscle strength.

Physical exercise is considered important for maintaining physical fitness including healthy weight building and maintaining healthy bones, muscles, and joints; promoting physiological well-being; reducing surgical risks; and strengthening the immune system.

Proper nutrition is just as, if not more, important to health as exercise. When exercising it becomes even more important to have good diet to ensure the body has the correct ratio of macronutrients whilst providing ample micronutrients; this is to aid the body with the recovery process following strenuous exercise. When the body falls short of proper nutrition, it gets into starvation mode developed through evolution and depends onto fat content for survival. Research suggest that the production of thyroid hormones can be negatively affected by repeated bouts of dieting and calorie restriction. Proper rest and recovery is also as important to health as exercise, otherwise the body exists in a permanently injured state and will not improve or adapt adequately to the exercise.

The above two factors can be compromised by psychological compulsions (eating disorders such as exercise bulimia, anorexia, and other bulimias), misinformation, a lack of organization, or a lack of motivation. These all lead to a decreased state of health.

Delayed Onset Muscle Soreness can occur after any exercise, particularly if the body is in an unconditioned state relative to that exercise.