Whether you're a marathon runner or a couch potato, you probably have some idea of how fit you are. But having more than a general sense of your fitness level can help you set fitness goals, monitor how you're doing and maintain your motivation.

The American College of Sports Medicine recommends that you assess four crucial components of physical fitness before you start a regular program of exercise. These include aerobic fitness, muscular fitness, flexibility and body composition. Set aside some time to calculate your scores (levels) in these four key areas. Once you know where you're starting from, you can plan where you want to go.

To assess all four of your fitness levels you need:

• A watch with a second hand or a stopwatch
• A cloth measuring tape
• A yardstick
• Heavy duty tape
• Someone to help you with the flexibility test

You also need a pencil or pen and paper to record your scores as you complete each part of the assessment. You can record these in a special journal you create to track your progress or move them to a spreadsheet on your computer.

Record your fitness levels (PDF file requiring Adobe Reader)

To assess your aerobic fitness, do a one-mile walk inside, outside or on a treadmill.

Start by checking your pulse
Before you start, check your pulse and record it. You can check your pulse over your carotid or radial artery. Here's how:

• Have your watch in front of you.
• Find your pulse by placing your index and third finger on your neck to the side of your windpipe, over your carotid artery.
• When you feel your pulse, look at your watch and count the number of pulses in 15 seconds.
• Multiply this number by 4 to get your heart rate per minute — for example, 20 x 4 = 80 beats per minute.

If your doctor has told you that you have a narrowed carotid artery, check your pulse at your wrist. Place two fingers between the bone and the tendon over your radial artery, which is located on the thumb side of your wrist. Even though you're checking your pulse over a different artery, you calculate your pulse rate in the same way.

Another option is to wear an electronic device that displays your pulse.

Take your walk
After you've recorded your pulse, note the time on your watch and walk one mile. After you complete one mile, check your watch and record the time it took you to finish in minutes and seconds. Then check and record your pulse once more.

Push-ups can help you measure muscular strength. If you're just starting a fitness program, do knee push-ups. If you're already fit, do toe push-ups. For both types:

• Lie facedown on the floor with your elbows bent and your palms next to your shoulders.
• Keep your back straight and push up with your arms to raise your body from your knees (or toes).
• Lower your body until your chest touches the floor. Make sure you keep your back straight.
• Then push your body upward, returning to where you started.

Count each time you return to the starting position as one push-up. Continue lowering and raising your body until you need to stop for rest. Record how many push-ups you complete before needing to stop for rest.

The sit-and-reach test measures the flexibility of the backs of your legs, your hips and your lower back.

Here's how:

• Secure a yardstick to the floor, placing a piece of tape across it at the 15-inch mark.
• Place the soles of your feet even with the 15-inch mark.
• Ask a friend or family member to place his or her hands on top of your knees to anchor them.
• Then reach forward as far as you can, holding the position for two seconds.
• Write down the distance you reached. Rest.
• Repeat the test two more times.
• Record the best of three reaches.

For a full assessment of the flexibility or range of motion of all your joints, see a physical therapist or athletic trainer.

To determine whether you're carrying too much weight around your abdomen, measure your waist circumference at its smallest point, usually at the level of your navel. Record your waist circumference with your other fitness scores.

A measurement of more than 40 inches (102 centimeters) in men and 35 inches (89 centimeters) in women signifies increased health risks, especially if you have a body mass index (BMI) of 25 to 35.

Your body mass index (BMI) is a measurement based on a formula that takes into account your height and weight in determining whether you have a healthy percentage of body fat. Be sure you record your BMI with the rest of your scores.

Keeping track of your progress is an excellent way to maintain your motivation. Assess all four fitness levels six weeks after your initial assessment and every three to six months afterward.

Repeat your assessment a year after your first assessment to see how far you've come. Celebrate your progress and set new goals.