"There are lies, damn lies and statistics" - Mark Twain or the latin translation to the Die has been cast. but I like a lot of Einstein quotes also.
A good one is
"If Men Define the Situation as Real, then it is real in it's consequences."
You can substitute man for human.
Also Dr. Seuss has some AMAZING ones! But depending on the situation you should check out Winston Churchill, Woodrow Wilson, JFK, and MLK Jr.
(sorry hard to pick one favorite)
"I am a man of very simple interest. I am simply satisfied with the best of everything" - Osho
Where you stumble - there lies your treasure. (Sorry, I don't know the author)
"Always be yourself, express yourself, have faith in yourself, do not go out and look for a successful personality and duplicate it."
making haste, slowly...
prepare for all days alike, when on the anvil bear,
& when you're the hammer, strike...
favor - kills faster than a bullet
et cetra, et cetra