Earlier quoted context omitted.
On the other hand that caveman wasn't doing the the same thing at the same pace of work every day of the year, and they had a much clearer idea of why the things they were doing were worth the effort they were putting in...
Presumably you are referring to work here, as the worth of anything you do in your personal life should be quite evident. You can find rewarding work.
Seems like a big assumption. I haven't yet, and I keep trying.