God called Jeremiah as “a prophet to the nations”, and He had to straighten out Jeremiah’s mouth before He could use him.
It is no different with you. You must understand that when God calls you to do something, you should not say you cannot do it. If God says you can, then you can! So often we speak out of our insecurities, or we verbalize what others have said about us, or what the devil has told us. Make a decision tonight that from now on you will say about yourself what God says about you.