"Who am I?"

Moses

So now, go. I am sending you to Pharaoh to bring my people the Israelites out of Egypt."

But Moses said to God, "Who am I that I should go to Pharaoh and bring the Israelites out of Egypt?" And God said, "I will be with you.  Exodus 3:10-12

Gideon

The LORD turned to him and said, "Go in the strength you have and save Israel out of Midian's hand. Am I not sending you?"  

"Pardon me, my lord," Gideon replied, "but how can I save Israel? My clan is the weakest in Manasseh, and I am the least in my family."  The LORD answered, "I will be with you."    Judges 6:14-16

"Then King David went in and sat before the LORD, and he said: "Who am I, Sovereign LORD, and what is my family, that you have brought me this far?" 2 Samuel 7:18

Jeremiah

The word of the Lord came to me, saying,

“Before I formed you in the womb I knew you,

before you were born I set you apart;

I appointed you as a prophet to the nations.”

“Alas, Sovereign Lord,” I said, “I do not know how to speak; I am too young.”

But the Lord said to me, “Do not say, ‘I am too young.’ You must go to everyone I send you to and say whatever I command you. Do not be afraid of them, for I am with you...

Amos

Amos answered Amaziah, “I was neither a prophet nor the son of a prophet, but I was a shepherd, and I also took care of sycamore-fig trees. But the Lord took me from tending the flock and said to me, ‘Go, prophesy to my people Israel.’ 

Johah

The word of the Lord came to Jonah son of Amittai: “Go to the great city of Nineveh and preach against it, because its wickedness has come up before me.”

But Jonah ran away from the Lord and headed for Tarshish. He went down to Joppa, where he found a ship bound for that port. After paying the fare, he went aboard and sailed for Tarshish to flee from the Lord. Jonah 1:1-3

But the Lord would not leave Jonah alone, because the message he was sent to give would help Jonah himself. He learned to conquer his fear and to realize the Assyrians were loved by God as well as the Jews. He learned that God would be with him. Traditional writings say that Jonah stayed in Ninevah teaching the Assyrians about the one true God.

The Lord used all these men who were humble. They did not think too highly of themselves, but were amazed that God had chosen them for a service. I think this is always the type of people God uses. If we think we can do a job well - without God's help - he cannot use us for that job.