Worst periods for me were when I had one clear, important goal, not particularly hard but hairy, and nothing else to do, sometimes because I myself cleared it up. I could spend months doing nothing useful, and end up very, very tired and burnt up.
I also several times had a conversation with managers, whom I told that I'd rather work on something very urgent, or otherwise give me something NOT (really) urgent and a big murky area of things to clear out which no one else knows how to deal with. That something won't probably be done, but that area will be improved a lot in creative ways. Typical managers' responses have been trying to micromanage my time up to personal hourly schedules, morning and evening personal reports, and scold me if I did anything out of the order of the list of priorities they imposed on me. Exactly the opposite of what's needed for me to be productive. And of course "let's just try that, and I'm not asking."
Next time I'll see such a response, I probably will quit on the spot; this is unbelievably cruel.
But it looks like the secret of the author is: just work in academia.