Hmmm, my character who's been cutting wood NONSTOP for over a year has no tiredness. He's not even using any sort of tool. We have problem, yes?
Then he is probably an expert lumberjack
Get the man an axe and get a careers started right away!
Well, with a little more research, we'll be able to determine if it is an individual trait, which will be good to know. Then, we can just kill off our characters that start with crappy tiredness. Creativly of course, no spawn and run thieves, but deaded none the less.
So it is allright to cheat as long as you do it in a creative way?
Since this game isn't about winning I see no reason to kill off characters for such reasons...