All discipline for the moment seems not to be joyful, but sorrowful; yet to those who have been trained by it, afterwards it yields the peaceful fruit of righteousness. (Hebrews 12:11)
If you think of this world as a place intended simply for our happiness, you find it quite intolerable: think of it as a place of training and correction and it's not so bad. (C.S. Lewis, God in the Dock)