Achieving health and remaining healthy is an active process. Effective strategies for staying healthy and improving one's health to an optimum level include the following elements:

Nutrition is the science that studies how what people eat affects their health and performance, such as foods or food components that cause diseases or deteriorate health (such as eating too many calories, which is a major contributing factor to obesity, diabetes, and heart disease). The field of nutrition also studies foods and dietary supplements that improve performance, promote health, and cure or prevent disease, such as eating fiberous foods to reduce the risk of colon cancer, or supplementing with vitamin C to strengthen teeth and gums and to improve the immune

System.

Between extremes of optimal health and death from starvation or malnutrition, there is an array of disease states that can be caused or alleviated by changes in diet. Deficiencies, excesses and imbalances in diet can produce negative impacts on health, which may lead to diseases such as scurvy, obesity or osteoporosis, as well as psychological and behavioral problems. Moreover, excessive ingestion of elements that have no apparent role in health, (e.g. lead, mercury, PCBs, dioxins), may incur toxic and potentially lethal effects, depending on the dose. The science of nutrition attempts to understand how and why specific dietary aspects influence health.

Sports nutrition focuses on how food and dietary supplements affect athletic performance (during events), improvement (from training), and recovery (after events and training). One goal of sports nutrition is to maintain glycogen levels and prevent glycogen depletion. Another is to optimize energy levels and muscle tone. An athlete's strategy for winning an event may include a schedule for the entire season of what to eat, when to eat it, and in what precise quantities (before, during, after, and between workouts and events). Participants in endurance sports such as the full-distance triathlon actually eat during their races. Sports nutrition works hand-in-hand with sports medicine.

Hygiene is the practice of keeping the body clean to prevent infection and illness, and the avoidance of contact with infectious agents. Hygiene practices include bathing, brushing and flossing teeth, washing hands especially before eating, washing food before it is eaten, sterilizing food preparation utensiles and surfaces before and after preparing meals, and many others. See personal hygiene, dental hygiene, and food hygiene.

Health care is the prevention, treatment, and management of illness and the preservation of mental and physical well being through the services offered by the medical, nursing, and allied health professions. According to the World Health Organisation, health care embraces all the goods and services designed to promote health, including “preventive, curative and palliative interventions, whether directed to individuals or to populations”. The organized provision of such services may constitute a health care system. This can include a specific governmental organization such as the National Health Service in the UK, or a cooperation across the National Health Service and Social Services as in Shared Care.

In alternative medicine, natural health is an eclectic self-care system of natural therapies concerned with building and restoring health and wellness via prevention and healthy lifestyles. Natural health includes diet, exercise, naturopathy, herbalism, natural hygiene, homeopathy, massage therapy, relaxation techniques (e.g. Yoga, Tai Chi), acupuncture, sauna, aromatherapy, ayurveda medicine, and Kneipp therapy.

Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals." 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 a 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 programs and distribution of condoms are examples of public health measures.