The most widely accepted definition of good health is that of the World Health Organization Constitution. It states: "health is a state of complete physical, mental and social well-being and is not merely the absence of disease or infirmity" (World Health Organization, 1946). In more recent years, this statement has been amplified to include the ability to lead a "socially and economically productive life." The WHO definition is not without criticism, mainly that it is much too broad.
The most solid aspects of wellness that fit firmly in the realm of medicine are environmental health, nutrition, disease prevention, and public health. These matters can be investigated at length and can assist in measuring well-being.
Health – level of functional and (or) metabolic efficiency of a person in mind, body and spirit; being free from illness, injury or pain (as in “good health” or “healthy”). The World Health Organization (WHO) defined health in its broader sense in 1946 as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."
Exercise – 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, and mental health including the prevention of depression. 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.
Life extension – The study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan.
Nutrition – provision, to cells and organisms, of the materials necessary (in the form of food) to support life.
Healthcare science – all the sciences related to the overall improvement of physical well-being of humans.
Medicine – science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness.
Dentistry – branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the mouth, maxillofacial area and the adjacent and associated structures (teeth) and their impact on the human body.
Obstetrics – medical specialty dealing with the care of all women's reproductive tracts and their children during pregnancy (prenatal period), childbirth and the postnatal period.
Psychiatry – medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities.