There's almost nothing that makes me feel as good as doing a hard workout.
Discussion
I get that feeling buying the Bitcoin. 
a cold river.
✊
Propagating new plants, something different than working on the computer - tangible results. This is a bunch of mulberry trees.
Wait until ETH implodes.
It's so ingrained in my daily routine that even if I'm injured (or in general pain bc I'm over 40 now), I still do it bc I somehow feel worse for having not done it
Do something hard everyday.