Updating here from `DM`:
I would add/clarify that mentorship, real-life reshaping of others and being reshaped, comes down to meaning. It hinges on real challenges.
A lot of the insanely gifted but almost haunted CEOs I know are like an engine at 7,000 RPM without the clutch down. There is a difference as you probably know between activity and movement. To really "feel tired out" in that good way, your challenge needs to completely break what you believe is possible, convince someone other than yourself you can do it, after you see through the limits, and then blast through the wall. Make a real change that takes a part of who you are to even attempt, and then feel the weight of the world on your shoulders enough to die happy every day, and just be in disbelief you even made it back to the bedroom in one piece.