I spend hours every day telling my clients what essentially boils down to this:
"Just 'cause you believe it, dos'ent mean it's true."
"When you are angry* you act angry, feel angry, you think angry, you have angry chemistry and you effect the world like an angry person. But afterwards when you calm down you know thats not the real you."
* insert any emotional state
"If you never do things, things won't get done."
"Other people can't read your mind, you have tell them."
"When you ask yourself: what if.......? (insert negative prediction), answer the question, don't sit there asking 'what if.....? over and over."
"Worrying is a habit, it's like smoking, you can quit"