It's Not Who You Are: It's Who HE Is.

Exodus 3:11 But Moses said to God, “Who am I that I should go to Pharaoh and bring the children of Israel out of Egypt?” 12 He said, “But I will be with you, and this shall be the sign for you, that I have sent you: when you have brought the people out of Egypt, you shall serve God on this mountain.” 13 Then Moses said to God, “If I come to the people of Israel and say to them, ‘The God of your fathers has sent me to you,’ and they ask me, ‘What is his name?’ what shall I say to them?” 14 God said to Moses, “I am who I am.” And he said, “Say this to the people of Israel: ‘I am has sent me to you.’” 

As Moses continues this conversation with God, he begins to realize the magnitude of what God is calling him to do, and the excuses begin to pile up: his inability to speak, his checkered past.  But this one really hits to the core: Who am I? When God answers to not worry about that, to trust in Him, Moses responds with Who are you? God answers with I am Who I am, He goes on to explain that He is the same One Who called out and blessed their forefathers.  It's not about us, but Him.