Optimal health always includes exercise. Physical fitness for young and old includes moving the body regularly in a wide variety of activities and range of motion. Directed and productive are running, weightlifting, yoga, stretching and aerobics. Recreational can include dancing, gardening and tennis. Testing is a scientific approach to the capabilities of one’s body under certain conditions and time. Rehabilitation is conducted after an injury, usually under the supervision of a physical therapist, or sometimes a fitness trainer who may also specialize in pregnancy or older populations. Health promotion is the most common reason for exercise, for its immunological effect, stress reduction, weight loss and psychological aspects.