(No dirty jokes please!)

I did a fancy breathing test at the doc's and am told the spot at which I'll be burning fat the most exclusively (rather than carbs and going anaerobic) is at 100 beats per minute. (I go into anaerobic metabolism at 120 bpm.)

So, until I find a heart rate monitor or try out one of the gym devices that have them built in, I wanted to ask generally what are you doing when your heart rate hits 100?

- Just strolling
- Brisk walking
- Housecleaning
- Sitting in a sauna reading and being lazy

or what?

Thanks.