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.
Non-athletes should mimic athletes' regimens more than we do.