Exercise systems and methods are provided that create and run exercise programs that are custom tailored to individual users. An exercise program for a specific user is based upon the user's average work heart rate and recovery heart rate. The exercise programs may include a series of workouts for the user to perform. Each workout requires the user to exercise at various intensity levels so that the user's heart rate moves between different predetermined target heart rate zones. The target heart rate zones are calculated from data relating to the user's average work heart rate and recovery heart rate. As the user's fitness level changes, the user's average work heart rate and recovery heart rate also change. Creation of new exercise programs uses the most current heart rate data to calculate the target heart rate zones, thereby continuously tailoring the exercise programs to the user.