Wear your heart rate monitor during every workout. The chest strap has a sensor in it that tells the watch what your heart rate is. Once you’ve figured out your ideal Fat Burning zone (we teach you how in the Program Guide under The Basics and on the Diamond Dozen Disc), simply check the watch readout regularly during your workout to determine if you’re in the zone or not. If you are, great. If your heart rate is too high, get into Safety Zone or modify the position to lower it.
The heart rate monitor can be a little complex if you’ve never used one before. I would ask you to go to read the instruction manual which walks you through how to activate and use the monitor easily.