Pope Shenouda III
If hunger presses on you, say to yourself that you do not deserve to eat.
Say to yourself: I do not deserve to eat because of my sins. You become inwardly humble when you are physically fatigued which allows you to pray in humility and help you to relinquish pride, vanity and self-complacency.
As for he who stands to pray in might, health and the strength of iron, where will submissiveness come from?