Finding the right exercise intensity level and staying there throughout a workout can help you get the most out of your sweat sessions. When you exercise in the zone, you burn calories more efficiently and avoid injuries. How can you tell if you're at the right intensity? Use your breathing as a guide with the scale below.

0 This is the way you feel at rest. There is no fatigue and your breathing is not elevated.

1 This is how you feel while reading or sitting at your desk. There's no fatigue and your breathing is normal.

2 This is what you feel like as you get dressed. There is little or no feeling of fatigue, and your breathing is still normal.

3 This is how you feel while walking across the room to turn on the TV. Your breathing is slow and natural. You might feel this way in the beginning of a workout.

4 This is the way you feel slowly walking outside. There is a slight feeling of fatigue and your breathing is slightly elevated, but comfortable. You should experience this feeling at the start of your warm-up.

5 This is how you feel while walking somewhere at a normal pace. You're aware of your breathing, which is now deeper, and there is a slight feeling of fatigue. You should experience this feeling at the end of a warm-up.

6 This is similar to how you feel when rushing to an appointment. Your breathing is deep and you're aware of it. This is how you should feel as you transition from warm-up to your regular exercise session.

7 This is the zone—try to maintain this level throughout your workout! There is a feeling of fatigue at this level, but you can maintain the intensity for the rest of your session. Your breathing is deep and you're aware of it.

8 Your breathing is very deep, and though you could carry on a conversation, you don't feel like it. You should only try to exercise at this level after you're feeling comfortable enough at level 7.

9 This is what you feel like when exercising very, very vigorously. Your breathing is very labored and it's tough to carry on a conversation. Take it down a notch.

10 This level is all-out exercise, so difficult that you can't maintain it for very long.

How Hard Are You really Working?, and other weight-loss and fitness tips from Bob Greene, Oprah's trainer.