Exactly. While I've slowed physically, my mind rarely stops (which can make it hard to sleep.) The head of my undergrad geology department introduced one of his classes this way: "My name is ______ _______. And we are going to study this (pick something geologic) because it interests me." I took the spirit of that as my philosophy for all fields of endeavor, ever since. (By the way, "something geologic" includes "life, the universe, and everything."