Marcus Aurelius

"If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment."

"Such as are your habitual thoughts, such also will be the character of your mind; for the soul is dyed by the thoughts."

"Waste no more time arguing about what a good man should be. Be one."

"In the morning when thou risest unwillingly, let this thought be present: I am rising to the work of a human being."

"Very little is needed to make a happy life; it is all within yourself."