Health, as defined by the World Health Organization (WHO), is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity."[1][2] This definition has been subject to controversy, as it may have limited value for implementation.[3][4][5] Health may be defined as the ability to adapt and manage physical, mental and social challenges throughout life.[6]

In the first decade of the 21st century, the conceptualization of health as an ability opened the door for self-assessments to become the main indicators to judge the performance of efforts aimed at improving human health[16]. It also created the opportunity for every person to feel healthy, even in the presence of multiple chronic diseases, or a terminal condition, and for the re-examination of determinants of health, away from the traditional approach that focuses on the reduction of the prevalence of diseases[17].
Do you smoke even a little? If so, know this: “Smoking even a single cigarette can induce changes that lead to a heart attack,” Gianos says. Lighting up increases your risk of atherosclerosis, raises your chances of blood clots, reduces blood flow and puts you at increased risk for stroke. But it’s never too late to quit and start reversing the damage. “Heart disease risk goes down 50% in the first year [after quitting] and becomes equivalent to a nonsmoker after 10 years,” Gianos says.
The environment is often cited as an important factor influencing the health status of individuals. This includes characteristics of the natural environment, the built environment and the social environment. Factors such as clean water and air, adequate housing, and safe communities and roads all have been found to contribute to good health, especially to the health of infants and children.[19][30] Some studies have shown that a lack of neighborhood recreational spaces including natural environment leads to lower levels of personal satisfaction and higher levels of obesity, linked to lower overall health and well being.[31] This suggests that the positive health benefits of natural space in urban neighborhoods should be taken into account in public policy and land use.
(US specific) Provided by an employer-sponsored self-funded ERISA plan. The company generally advertises that they have one of the big insurance companies. However, in an ERISA case, that insurance company "doesn't engage in the act of insurance", they just administer it. Therefore, ERISA plans are not subject to state laws. ERISA plans are governed by federal law under the jurisdiction of the US Department of Labor (USDOL). The specific benefits or coverage details are found in the Summary Plan Description (SPD). An appeal must go through the insurance company, then to the Employer's Plan Fiduciary. If still required, the Fiduciary's decision can be brought to the USDOL to review for ERISA compliance, and then file a lawsuit in federal court.
Health science is the branch of science focused on health. There are two main approaches to health science: the study and research of the body and health-related issues to understand how humans (and animals) function, and the application of that knowledge to improve health and to prevent and cure diseases and other physical and mental impairments. The science builds on many sub-fields, including biology, biochemistry, physics, epidemiology, pharmacology, medical sociology. Applied health sciences endeavor to better understand and improve human health through applications in areas such as health education, biomedical engineering, biotechnology and public health.
The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress".[7] Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity".[8] Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.[9]