Maintaining health
Personal health depends partially on one's active, passive, and assisted observations about their health in their everyday life. The information gleaned from such observations may be used to inform personal decisions and actions (e.g., "I feel tired in the morning so I am going to try sleeping on a different pillow"), as well as clinical decisions and treatment plans (e.g., a patient who notices their shoes are tighter than usual may be having exacerbation of left-sided heart failure, and require diuretic medication to reduce fluid overload) for patients who share their observations with their health care providers.
Personal health depends partially on the social structure of one's life. The maintenance of strong social relationships is linked to good health conditions, longevity, productivity, and a positive attitude. This is due to the fact that positive social interaction as viewed by the participant increases many chemical levels in the brain which are linked to personality and intelligence traits.
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organised efforts and informed choices of society, organizations, public and private, communities and individuals." (Winslow, 1920)[citation needed] It is concerned with threats to the overall health of a community based on population health analysis. The population in question can be as small as a handful of people or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). Public health has many sub-fields, but is typically divided into the categories of epidemiology, biostatistics and health services. Environmental, social and behavioral health, and occupational health, are also important fields in public health.
The focus of public health intervention is to prevent rather than treat a disease through surveillance of cases and the promotion of healthy behaviors. In addition to these activities, in many cases treating a disease can be vital to preventing it in others, such as during an outbreak of an infectious disease. Vaccination schedules and distribution of condoms are examples of public health measures.