Chronic diseases have become a focal point of public health worldwide with estimates of trillions of dollars in annual health care cost and causing more than 36 million deaths a year. Lifestyle factors such as physical inactivity are heavily correlated with the development of many chronic diseases. New strategies for primary and secondary disease prevention are desperately needed to aid in blunting the negative economic and social impact of these diseases. Physical activity (PA) and exercise are now considered principal interventions for use in primary and secondary prevention of chronic diseases. Currently, more emphasis in primary prevention of disease is necessary to reduce disease risk in youth and adults; however with chronic disease prevalence so high, similar emphasis is also necessary for secondary prevention in those children and adults already inflicted with chronic diseases. Conditions such as cardiovascular disease, type 2 diabetes, obesity, and cancer are drastically improved when PA and exercise are part of a medical management plan. In addition, the national PA guidelines in conjunction with PA promotion tools like Exercise is Medicine™ are needed to promote increased PA and exercise levels worldwide.