Along the same lines....
I just purchased a heart rate monitor and it has been a lifesaver. It was amazing to see how quickly I would "fall" out of my zone. It makes one realize how often we exercise in an anaerobic state - which is why many of us exercise and don't see the fat burning results we are looking for.
It took me some time to research different models and find one appropriate for me (obese). If you want to know which model I purchased - "PM" me. I don't want to list it because I am not sure if listing it would be considered advertising?? No, I don't sell them.