My cardio doctor recommended that I don’t let my heart rate go above 150 bpm and not do do things like pull ups. I have a tissue valve in the aortic position and everything is good. I’m really missing pushing my exercise to the maximum, it’s fun for me. I used to ride my bicycle for hours at 150 and when I hit a steep hill I could keep it at 180 for 30 minutes maxing out at 192. IS MY CARDIO DOC OVER CAUTIOUS?