David fought Goliath and won.... He didn't just knock Goliath down, he cut off Goliath's head with his own sword!
David wasn't the most skilled warrior on the field, he was just the delivery boy... but he had an awarness of his advantage that nobody else did. He didn't fight by himself or for himself, but he came in the name of the Lord Almighty!
You have that same advantage, you just need to learn how to become aware of it!