The leading cause of death of police officers is heart disease, which results from job stress, improper diet that includes fast foods, and not enough physical exercise. Despite widespread knowledge of this problem, few police agencies have initiated mandatory physical training requirements. In addition, research has revealed that many police officers are in such poor physical condition that they are at high risk of serious health problems. To address these problems, the sheriff's department of Jacksonville, Fla. has established a physical fitness program that uses reinforcement and motivational techniques to keep police officers active.