The growing popularity of personal fitness can be observed in the increasing number of exercise centers and spas, and the burgeoning amount of lay literature. It is estimated that 50 percent of adult Americans engage in some form of regular exercise, but many have little or no concept of what constitutes a safe, effective fitness program. Many advertisements make attaining fitness look almost effortless. This leads the novice to unrealistic expectations. Few health care providers receive formal training in fitness management. As a result, their instructions are often vague. This article discusses the components and importance of personal fitness. Possible risks of exercise are also discussed. The normal physiologic responses to exercise and training are reviewed and the necessary ingredients of an effective fitness prescription presented. Motivational aspects are explored, using the health-belief model as a framework.