If you’re anything like most men, you exercise to lose weight, increase your stamina, or boost your heart health. These are good reasons! The one thing you don’t want to do is waste your exercise time. If you’re not pushing yourself enough, you might as well not go. Push yourself too hard, however, and you’re likely to visit the doctor that same week. It’s all about balance. Part of that balance comes from understanding your heart rate — the number of times your heart beats in a single minute. Your target rate, according to the American Heart Association, should be between 50 to 85 percent your maximum rate. Men can find this by subtracting their age from 220. For example, if you’re 40, your max heart rate is 180. Your target rate is 180 multiplied by .50 or .85. This makes your target rate between 90 and 153.