For me that’s one of the most important points made here. The human body and mind is incredibly complex and we are all different. You really have to try out what works for you personally.
Sleep and wake cycles are probably one of the most obvious examples here. Just because some successful entrepreneurs swear by waking up at 4am every day does not mean that works for you. (I can barely spell my name anything before 9am). That’s why I think that the most important thing you can do with anything you read, hear or get told is to try it out for yourself and make adjustments. Be bold enough to say this works for me or this doesn’t. Trust yourself.
Also, what works for you now might not work in a year from now. Externalities change. People change. You change. And that’s why, as you said, you need to monitor your habits and to practice mindfulness and awareness.
Self-improvement isn’t a one time adventure, but a lifelong journey.