SOVEREIGN

God is sovereign. He can do what he want to do, when and how he want to do it, and use whomever he chooses.
So if God called you to do something, stop giving him excuses. He knows all about you and your capabilities. He created you. Trust, if God told you to do it, he will also equip you to do just that. He will send the right people to help you, as well.
Ask me how I know, because He told me to write a book, and I wrote a book. Then he told me to publish the book, I had no idea how to publish a book, and no money to finance publishing a book, but God!! The book is now on Amazon.com and another is on the way. 
If God can take this woman right here, with all her faults, her horrible past, and equip her to write and publish a book for his glory, to call her to spread the gospel of Jesus Christ, he can and will equip you to do the very thing he has shown you. Stop giving him excuses! God is sovereign!