I tried out a friend's HRM last Sunday and have never had a more frustrating yet interesting run. FWIW, I hereby declare that I don't believe anybody can tell their HR without a monitor, at least without a lot of practice with one. I thought I was running easily within my Maf zone based just on easy nose breathing and easy conversation. Nope. Way over. I have to believe and pray that my body will adjust to running while holding within the zone. In my case that's 122 BPM (180 - 58). Please, somebody, feel free to reassure me!