Introduction
Any behaviour that affects a person's health status, either positively or negatively, is considered to be a health-related behaviour. Daily habits involving diet, exercise, safety practices and substance use are not only related to the prevention of disease, but also affect the management of chronic illness and degree of disability (Fries, 2002). It is difficult to imagine any activity or behaviour that does not affect our health in some way, either directly or indirectly.
Common health-related behaviours include diet, exercise, smoking, alcohol use, safety practices and participation in health screening examinations such as testing for cholesterol levels, breast and prostate cancer (Fishbein et al., 2001). Among the health-related behaviours most often encouraged in health promotion programmes is regular physical exercise because of its positive impact on health, disease prevention, psychological wellbeing and overall longevity (Johnson, 2003). Regular physical activity is associated with lower death rates for adults of any age, even when only moderate levels of physical activity are performed (Center for Disease Control, 1999). Regular physical activity decreases the risk of death from heart disease, lowers the risk of developing diabetes, reduces the risk of colon cancer and helps reduce blood pressure (Center for Disease Control, 1999). In 1999, only 65% of adolescents engaged in the recommended amount of physical activity. Even more disappointing, in 1997, only 15% of adults performed the recommended amount of physical activity, and 40% of adults engaged in no leisure time physical activity (Center for Disease Control, 1999).