“The mind is everything. What you think you become.”
“Thought is the sculptor who can create the person you want to be.”
“The ancestor of every action is a thought.”
“A man is literally what he thinks, his character being the complete sum of all his thoughts.”
“For as he thinketh in his heart, so he is.”
OK, I said five…but here’s one more.
“We are shaped by our thoughts; we become what we think. When the mind is pure, joy follows like a shadow that never leaves.”
Urban Simplicty 
I'll have to give that some thought.