'Unfit' in the Bible

Do you not know that God's people will sit in judgement upon the world? And if you are the court before which the world is to be judged, are you unfit to deal with these petty matters?

But [like a boxer] I strictly discipline my body and make it my slave, so that, after I have preached [the gospel] to others, I myself will not somehow be disqualified [as unfit for service].