"The producer of old age is habit: the deathly process of doing the same thing in the same way at the same hour day after day, first from carelessness, then from inclination, at last from cowardice or inertia.
Habit is necessary; but it is the habit of having careless habits, of turning a trail into a rut, that must be incessantly fought against if one is to remain alive... one can remain alive long past the usual date of disintegration if one is unafraid of change, insatiable in intellectual curiosity, interested in big things, and happy in small ways."
