I don't think a machinist falls into what your parent-post was getting at. I have found skill and 'puzzle solving'(using Allen's analogy) in menial or physical

I don't think a machinist falls into what your parent-post was getting at. I have found skill and 'puzzle solving'(using Allen's analogy) in menial or physical labour. But as stated, your body just can't take it. And you realize you're spending your off time tired, sore and wasted. A machinist is solving problems and puzzles. A street sweeper or machine man on an assembly line aren't.