Wellness refers generally to the state of being healthy, but by the late 20th century, became, as well, a description of the interest in the more affluent nations to adopt behaviors which prolong and enhance the state of being healthy, and by extension, the lifespan itself.
Wellness, in this sense, is subjective, the perception of being healthy, rather than any investigatable "reality" of being healthy. The behaviors in the pursuit of wellness sometimes include proven methodologies, but may also include practices with no scientifically proven capacity to increase health.
Wellness, as a concept and a practice, is found in more affluent societies because it involves managing the body state after the more basic needs of food, shelter and basic medical care have already been met. Many of the practices applied in the pursuit of wellness, in fact, are aimed at controlling the side effects of affluence, such as obesity and inactivity - leading to lack of exercise.
Wellness grew as a popular concept starting in the late 19th century, just as the middle class began emerging in the industrialized world, and a time when a newly prosperous public had the time and the resources to pursue wellness and other forms of self-improvement. Many early consumer products, from corn flakes to mouth wash, derived from or exploited the emerging interest in wellness.
Wellness can include using scientifically-based tests and practices to maintain health, as in checking cholesterol, blood pressure, glucose, and other body indicators. Or it can include unproven practices, such as avoiding certain foods or taking certain vitamins or alternative medicines.
The subjective nature of "wellness" can be illustrated by the hypothetical example of an individual who avoids food additives and is selective in choosing foods to prolong health, but thinks nothing of getting in a car and driving hundreds of miles. Statistically, the known risk of mortality or morbidity from automobile usage is far greater than the risk of
mortality or morbidity from food additives, but avoiding certain foods and food additives feels "healthy," whereas avoiding automobile use feels merely inconvenient.
Even when the techniques used are not scientifically proven, the pursuit of wellness can enhance health by a placebo effect. Someone who feels "well" may lower stress and enhance their sense of well-being, achieving an enhanced psychological state with proven beneficial effects on various body systems, including blood pressure, gastrointestinal system functioning, and immune response. The field of psychoneuroimmunology explores these linkages in a scientific manner, and is also a part of medicine proper. However it is new, and still exploring the biology, and has little or no clear advice to offer other than to avoid unnecessary stress or that which is out of one's control or capacity.
Wellness is thought by most to be closely related to wealth, either because one must control resources to avoid stress, or because wealth itself cannot be enjoyed unless one is well, and therefore one can be potentially both in command of resources and suffering a sort of sensual or stressful poverty at one and the same time. It is sometimes observed that even rich people who take on too many commitments often have just as little free time as the poor - and may very easily outrun their resources.
Wellness has developed into a buzzword used by the Network Marketing and Multi-Level Marketing "communities" to sell unproven health supplements and quack cures.