To keep the spirit of eternal youth active in us during the second half of life, we must learn again to play with our experience. Recall the joy of discovery before it bowed to work, obligation, and duty. Movement is alive; inertia is dead. We become more “unalive” as we cling to that which is predictable and unchanging. Enthusiasm is closely related to the spirit of play – the word comes from the ancient Greek theos, meaning “god.” To have enthusiasm is to allow yourself to be filled with divine assistance, so the ego does not need to handle your tasks by itself.
– Robert A. Johnson, from Living Your Unlived Life