The Surgeon General's report discusses the importance of daily physical activity and addresses the role of schools' physical education programs in implementing activity into every child's life. Professionals in the physical education field have typically used three domains to address the physical education curriculum: motor, cognitive, and affective, however, Annarino and colleagues proposed that a fourth domain--fitness--should be considered. In this article, the authors provide the rationale for the fitness domain and outline how this health-related component fits into a physical education curriculum. Properly acquiring and implementing fitness-related information requires time and effort from the physical educator and his or her students. However, this information has lifelong implications and is vital if the goal is to improve overall fitness. Therefore, fitness should be considered to be the fourth domain of physical education, and deserves the same focus as the other three domains.