I finally broke down and got a heartrate monitor a few weeks ago....always preferring to go "organic" before that. How do I find my personal max heart rate? Do I simply warm up on the trainer and then go like hell, seeing how far I can push it. How long should I be able to hold it before it becomes the max HR, or does the fact I can't hold it indicate the max HR? And I assume more than one effort on different days would be good?