Aphorism, n.: A concise, clever statement you don’t think of until too late.
For every time we regret keeping still, there are about ten times we regret speaking up.
A closed mouth gathers no foot.
Probably the most honest "self-made person" ever was the one we heard say: "I got to the top the hard way - fighting my own laziness and ignorance every step of the way."
Too often we seek justice for just us.
Whether a character in your novel is full of choler, bile, phlegm, blood or plain old buffalo chips, the fire of life is in there, too, as long as that character lives.