I know people who act like they're great. Casually mentioning whatever success they've recently had or their most recent purchase, etc.
I know people who don't worry about how they act - they just ARE great. They do great things.
Sometimes I catch myself acting instead of doing great things.
You were put on the earth to do great things, not tell people how great you are.
Do great things - let your actions speak for themselves.
(This blog post is written to me more than anyone else)