You can use heart rate zones to control the intensity of your workout. This will help you make sure that what you’re doing is aligned with the purpose of your workout and adjust the intensity of your workout accordingly. Training with heart rate will allow you to monitor that your exercise intensity is just right during different parts of your workout (warm-up, steady-state, high intensity, cool-down). For example, by exercising in a low heart rate zone, you’ll improve your steady-state endurance and teach your body to use fat as energy, whereas working out in heart rate zone 4 will increase your speed endurance.