@HedgeMage Getting Things Done by David Allen. Also "Subtle Art of Not Giving a F*ck" as an intro to mindfulness and not taking things too seriously. Also liked Focus by Leo Babauta but it's a little dated.
@hedgemage It's perhaps a little left field but Lessons Learned in Software Testing is a pretty good book to get context on what testing really is, something programmers tend to be ignorant about. I'm a bit biased since I'm partly a tester, but learning a bit about testing is learning a bit about lisp, it can give you a broader perspective on problems.