The flip side of focused mode thinking is diffuse mode thinking, and they are symbiotic. Your brain needs a chance to work silently in the background on hard problems while you do other things (walk, sleep, play with the kids). Then when you re-enter focused mode, you are fresh and your brain often presents solutions uncovered during your diffuse time.
This concept is articulated really well in "A Mind for Numbers":
Being able to tell when you are frustrated is such a powerful tool. Doing literally anything else will be more productive in and of itself, but it also opens the window to let a little diffuse thinking sneak in.
How many times have you done an hour worth of work one morning to untangle a mess you made the previous afternoon? Diffuse thinking saved you. Invite it in.
This concept is articulated really well in "A Mind for Numbers":
https://www.goodreads.com/book/show/18693655-a-mind-for-numb...