Hundreds of books refer back to the book Flow written by Mihaly Csikszentmihalyi. Indeed is his life's work, an example of an author who discovered a purpose greater than himself which fueled years of effort to produce a landmark contribution to personal growth.
Mihaly used his book Flow as the vehicle to positively impact millions of lives in a significant way.
A state when you are so engaged in an activity that nothing else seems to matter. The experience itself is the reward - where the enjoyment stems from sheer sake of doing it.
Is it possible to engage in your life in this way? Meaning that you are so engage it life itself that the enjoyment of it all stems from engagement in totality of it all?
I'd suggest reading some of the shared Kindle highlights of Flow here.