Any activity undertaken by an individual, regardless of actual or perceived health status, for the purpose of promoting, protecting or maintaining health, whether or not such behaviour is objectively effective towards that end.
Reference: Health Promotion Glossary, 1986
It is possible to argue that almost every behaviour or activity by an individual has an impact on health status. In this context it is useful to distinguish between behaviours which are purposefully adopted to promote or protect health (as in the definition above), and those which may be adopted regardless of consequences to health. Health behaviours are distinguished from risk behaviours which are defined separately as behaviours associated with increased susceptibility to a specific cause of ill-health.
Health behaviours and risk behaviours are often related in clusters in a more complex pattern of behaviours referred to as lifestyles.