Also, my samsung watch can measure stress (whatever it means). It always shows the very, very minimal stress for me. The only time that I have been stressed was the day that I spent a bit too much on the steam room.
Zone 2 is great but the best health outcomes are from people who do high intensity exercise interspersed with zone 2 exercise.
HIIT is quite effective at something; it's not clear that it is effective at all possible exercise goals (including, but not limited to, endurance running).
Johnson in particular says that unless you've already narrowed the gap between your "first" and "second" (anaerobic) threshold to 5%, HIIT really doesn't make much sense because you're "aerobically challenged" and need to work on that first, which he believes (with significant evidence) is best done almost entirely in zone 2.
He also notes that someone like Eliud Kipchoge can spend 2 hours running 4:30 min/mile pace, so that is clearly within his aerobic range, but that Kipchoge would never and should never spend much time training at that pace because of the load it would put on his system. So the zones that are used for training purposes depend significantly on the current fitness level of the athlete.
I have used HIIT effectively to get myself out of certain fitness/training "ruts", but I think that the zone 2 folks have somevery cogent and coherent observations and advice.
For example, if I do a week of 3x30 minute swssions at Zone 2, my fitness is going to plummet. But if I do one at Zone 2, one at tempo, and one set of intervals, I'm at least maintaining fitness.
Would 5 hours at zone 2 be better? Absolutely. But I dont always have the time.
If your long term average is 180 minutes a week of cardio, you're not an advanced endurance athlete. You're probably middle of the pack in the fun run.
No offense, that's still admirable, but you can use your time much better than just doing only zone 2.