The two claims I remember most from The Art of Learning are:
A lot of people seem to have absorbed (1), whether or not they actually enact it. I rarely see people discuss (2), and I think that's a shame, for a few reasons:
I haven't undertaken any projects that involve measuring my recovery, but anecdotally, it seems to be very important. For example, planking gets a lot harder if I so much as hold my phone between sets. (It's said that Justin Verlander doesn't raise his arm above his shoulder on his rest days; I don't know whether that's true, but I hope it is.)
In my most recent (abandoned) attempt at a podcast, I asked various high performers how they recover; I didn't get many good answers. The best and most entertaining was from Byrne Hobart, who says that he recovers from reading by reading different things. Mostly I just admire the work ethic, but I also think there's something to the idea of what Ryan Holliday calls "crop rotation:" sometimes different kinds of work can complement each other so that you can make progress on another while recovering from one.
By the way, this tweet of Byrne's prompted me to write this up; please do reply to that tweet or to me (contact information is on my home page) with any useful reading material.
Non-athletes should mimic athletes' regimens more than we do.