Interest in behaviors that have important impacts on our health and well being is based upon
two assumptions; (a) that a significant proportion of the mortality from the leading causes of
death is caused by the behavior of individuals, and (b) that such behavior is modifiable
(Conner and Norman 1996). Behavior is held to exert its influence on health in three basic
ways: by producing direct biological changes, by conveying health risks or protecting against
them, or by leading to the early detection or treatment of disease (Baum and Posluszny 1999).