A brother asked Abba Poemen, saying, “For what purpose were spoken the words, ‘Take no thought for the morrow?’ (Mat 6:34) The old man said unto him, “For the man who is under temptation, and is in affliction; for it is not right that such a man should take thought for the morrow, or should say, ‘How long shall I have to endure this temptation’, but he should think upon patient endurance, saying: ‘It is today, and the temptation will not remain thus for a long time.'”

[Abba Poemen, Apophthegmata Patrum]