If you don't have one of these, GET ONE! They are a lifesaver. You put in your age, height, weight, etc and it will give you your target heart rate, workout schedule, and an ACCURATE count of how many calories you burned during your workout. I use this one ^ it's super easy to use and worth every penny. During my cycling class I kept within my target heart rate so I didn't feel totally spent after the 60 minutes PLUS I burned a little over 500 calories. Will I partake in the wonderful world of cycling again?