Health-related physical fitness is defined as fitness related to some aspect of health. This type of physical fitness is primarily influenced by an individual's exercise habits; thus, it is a dynamic state and may change. Physical characteristics that constitute health-related physical fitness include strength and endurance of skeletal muscles, joint flexibility, body composition, and cardiorespiratory endurance. All these attributes change in response to appropriate physical conditioning programs, and all are related to health.
Organised noncompetitive walking is extremely popular in the United States and Europe. Millions participate for the relaxation and exercise it offers. Walking for recreation or fitness is differentiated from hiking by its shorter distances, less challenging settings, and the lack of need for specialized equipment. Walking can simply be an unorganized meander around a local park or trail for relaxation or a daily regimen of several miles that is undertaken for health benefits.
("walking." Encyclopædia Britannica. Encyclopaedia Britannica 2008 Ultimate Reference Suite. Chicago: Encyclopædia Britannica, 2008.)