It's not up to me to judge my own worth. That decision is made in the minds of everyone who watches what I do. That decision is never directly told to me.
I don't talk about how great I think I am. I just try to do what I think is right. If I'm great, I will demonstrate it with my deeds. Sometimes someone will come along who disagrees with what I'm doing, and they will call me many insulting names. During those times, there is little point in defending myself by explaining how great I am. If I've truly been great, many others will do that on my behalf.
And that's how I know that I'm doing things well.