Health is not simply the absence of disease or injury. Health is the ability to interact successfully with the environment in order to engage in meaningful, productive, satisfying activities throughout one’s life. Health and wellness are viewed as the ability to adapt to changing environmental demands and biological, psychological and environmental challenges.

Humans have an intrinsic occupational nature that is evident throughout the lifespan. Occupation, in the form of work/study, play/leisure, and self-maintenance (including rest and sleep), is essential for normal development and physiological and psychological well-being. The value and meaning of occupation is individually determined and influenced by personal, sociocultural and environmental factors. The ability to select, organize and perform activities influences one’s health and brings about feelings of mastery and competence. Occupational performance is influenced by the individual's repertoire of abilities and skills, and by physical, social, cultural, and economic aspects of the environment. All individuals, regardless of any disease or injury, can develop a repertoire of skills and abilities to achieve personal goals and experience feelings of competency.

Occupational dysfunction occurs when an individual is unable to interact with, and/or meet the demands of, the environment effectively and successfully. The therapeutic use of occupation and/ or adaptation of the environment can improve occupational performance and facilitate the acquisition or reacquisition of meaningful life roles. Occupational therapy is a health profession committed to enhancing occupational performance and quality of life by promoting and restoring health through active engagement in purposeful, meaningful occupation. Occupation, including its interpersonal and environmental components, may be used to prevent and mediate dysfunction and to elicit maximum adaptation. Active participation in meaningful activity is both a therapeutic tool and a therapeutic goal in occupational therapy.