"Believe you can and you're halfway there." Theodore Roosevelt.
That means you have to think you can do it before you can actually do it. It won't just happen, you have to believe. I have to believe I can get an A or score a goal before I get an A or score a goal. It can change your life because you will do so many things you didn't know you could. You'll become more optimistic, which is a good thing. With more optimists the world will advance in technology, art, and all the rest of life. We'ld be more advanced than we ever thought imaginable.