A positive state of mind engendering a sense of well being that enables a person to function effectively within society. Individuals who have good mental health are well-adjusted to society, are able to relate well to others, and basically feel satisfied with themselves and their role in society.

Breakdown of mental health is a major problem in Western societies: it has been estimated that at least one in four adults will suffer from some form of mental disorder, such as depression, during their life. Many physicians and psychologists believe that individuals are physical, mental, and spiritual beings and that these aspects are interrelated. Consequently, mental health is not possible without both physical and spiritual health.

Although there is no clear cause-and-effect relationship between exercise and mental health, aerobic exercise can improve self-esteem, lessen anxiety, and relieve depression. Exercise can act as a form of meditation, changing the state of consciousness and providing a distraction from stressful situations. Many doctors believe that exercise improves mental health and prescribe exercise to relieve depression and anxiety. Walking is the most frequently prescribed exercise, followed by swimming, bicycling, strength training, and running.