Take a look at some of @cryptogee's previous posts listed here. He's been exploring this topic in depth for awhile and these posts offer a lot.

I also have been fascinated with this topic for most of my adult life and have found Qi Gong to be an unparalleled tool for increasing the flow state possibilites in each day. I also meditate and do some yoga everyday so maybe it's the combo of all three I'm not sure but none of these practices takes much time and all give back exponentially.