yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."
Seem to remember another Roosevelt one
Don’t hit at all if you can help it; don’t hit a man if you can possibly avoid it; but if you do hit him, put him to sleep.
That's in a similar vein to what a martial arts teacher told me...
Rule 1. Don't get hit.
Rule 2. If you are going to get hit, hit him before he hits you.