At the end of your career you're trying to find a point to it all, and at the start of it you're looking for a purpose.
Possibly the most important thing to a human being, once he is alive and possessed of the means of sustaining life, is that he should do the work he cares most to do and is best capable of doing.
On such jobs men become tired. They experience a weariness beyond fatigue. They say mad, brilliant things. Out of my head, I cussed and talked and cracked jokes and sang. Hell boils with laughter.
A man is not idle because he is absorbed in thought. There is visible labor and there is invisible labor.