When you exercise, it's important to work at an intensity level that's right for you. This is known as your target heart rate. The target heart rate is the range in which you can exercise safely, while receiving the maximum cardiovascular benefits. When you work out, it's recommended that you maintain this rate for 30 minutes, at least three times a week. Your target heart rate will depend on your age, and how well-conditioned you are. First, determine your maximum heart rate by subtracting your age from two hundred and twenty. This number is the maximum number of times your heart can normally beat in one minute. If you're just starting an exercise program, it's recommended that your target heart rate be between 50 and 75 percent of your maximum heart rate. After six months, you may be able to increase your target heart rate. Ask a doctor for exact guidelines. The easiest way to check your heart rate or pulse is to place the tips of your middle and index fingers in the groove of your throat, just to the side of the Adam's apple. Count the number of beats for ten seconds, and then multiply that number by six. If you're not within your range, you may need to adjust the intensity of your exercise up or down to reach your target heart rate. Remember, your target heart rate is only a guide, so listen to your body for signs of injury or over-exertion. If you're over 35 or have medical problems, be sure to check with a doctor before beginning any exercise program. For more information on target heart rate, consult a health care professional.