What is your favorite quote of all time?

I do think of this quote as being something awesome that Picard said, but something also bugs me when I think of it that way... I'm attributing a great line, and advice I follow a lot through life to a fictional character, instead of to the man that actually said it.

David Kemper wrote that episode of TNG, and while he may have heard it elsewhere or paraphrased it from a common saying in some distant land or who knows, at least we can attribute it to him as best we can :-)