People love documenting but hate doing because with documenting, there is certainty.
Would you rather do a jigsaw puzzle where you know you have all the pieces, or one where you are merely hoping you have all the pieces? What if doubt creeps in?
The trick here is realizing that with most things you do, it's actually pretty trivial to finish the puzzle if you just trust that there's a way.
a Schelling point for those who seek one