The quote I picked is this: "Believe you can and you're halfway there." -Theodore Roosevelt. I chose this one because I believe it is absolutely true. It means that deciding you can do something is just as hard as actually doing it. Telling yourself and others this simple sentence provides enough encouragement to get "halfway there," so to speak. As for changing the world, many worldwide problems could be solved just by understanding this message. I hadn't heard this quote before now, but I can now apply it to many things.