I came across the following while web surfing. It doesn't seem to have any elevated origin, besides an anonymous person trying to be clever (and in this case succeeding).
Predict everything, expect nothing.
I like it.
"Predict everything, expect nothing" is a perfectly good axiom. I take it to mean, "plan your future as best you can, but don't be disappointed if and when the plans don't work out right -- they seldom will -- and learn to roll with the punches." But of course it's a lot snappier than my paraphrase.
Let's get behind this and try to make a cliché of it. I predict success for that endeavor. But of course I don't expect it.