According to Google, Bill Wilson gets credit for this quote but I have heard the premise many times before. What is easier to change at first, your mind or your behavior? In a classroom full of kids, I think we would all agree that you set the expectations for certain behaviors and the benefits of those behaviors cause kids to believe in them!
I always think about James, a great kid I taught in fifth grade. He hated the idea of "hands on" math. He thought that little blocks were for little kids, not fifth graders. He wanted to learn how to do fractions and decimals on paper. I wanted him to deeply understand how three fifths and 60% were the same. Anytime he needed guidance with his learning, I didn't hesitate to pull some kind of blocks out of my Home Depot tool belt. (Yes. I wore one!)
At first, he would reluctantly work with me. He experienced success even though his attitude said it was wrong. After a short time, I saw him grabbing his own set of blocks to work things out. Victory! As his teacher, I changed his behaviors which eventually changed his mind.
More than not, if you need to change your attitude, change your behaviors first. Your mind will follow!