The Book of Jonah never fails to cheer me up or give me a smile. Filled with irony and a sense of humor, sad sack Jonah is forcibly transformed from runaway to evangelist - the most successful evangelist of his day. All of Ninevah repents...to Jonah's bitter disappointment that the Ninevites averted fire and brimstone.
The king surely must have been tempted to despair, but when he himself fasts and does penance and orders the people to do the same, he concludes, "Who knows, God may relent."
It's never too late in Nineveh or now. Surely God will accept our Lenten repentance and hopelessness or inertia should not tempt us to think otherwise.
But a "Who knows?" attitude before any major endeavor is helpful too. It seems far more healthy than an invincibly powerful "can do" attitude, or the opposite extreme of "what's the use?" Who knows, with God's help, it's surely worth setting out on a great adventure.