same as many here, I've been off the bike for a month here and there after having a few ops over the last couple of years, its my heart and lungs conditioning that goes most easily too. I'm still not right & needing another op. I need to take a few more days rest here and there with the discomfort & I'm not riding at full capacity to really get my heart rate and breathing back as was, allied to still fuelling myself nearly as much as when doing more longer & faster runs, so a double whammy of misfortune and my own poor willpower/stupidity is making every ride a bit harder than it should be or needs to be.