Contemporary thinking in public health posits that childhood and adolescent physical activity and physical fitness may influence health status during childhood and adolescence, as well as throughout adulthood. This paper addresses the evidence dealing with potential associations of physical activity and physical fitness in childhood and adolescence to health status during childhood, adolescence, and adulthood. There are generally low to moderate relationships between childhood and adolescent physical activity and health (operationalized largely in terms of health-related physical fitness) and adult physical activity and health. A large part of the variability in health-related fitness is not accounted for by physical activity as assessed in the available studies. Nevertheless, the trends emphasize the importance of a lifestyle of regular physical activity during childhood and adolescence, which continues into and throughout adulthood, for the health and well-being of the individuals and populations.