Right, that’s the “menial” in the previous sentence to your quote. Washing dishes, cleaning floors, routine stuff where the mind can wander. For me when I was younger this was driving a mower around and around and around — not really intense physical labor, just a rote mechanical job that doesn’t consume much mental capacity.
I’m not a door pro, but my experience with diying doors puts it definitely NOT in the category of mindless!
Really depends on what kind of labor is it, not all of it is equal. I've had a new doors installed in my apartment yesterday, and the amount of troubleshooting and stress that the installers went through is not smaller than what I've faced in my programming job. But, I didn't have to do it while sweating from lifting 100 kg doors onto fourth floor, and later repeatedly trying to wrangle them into place.