I freeze when it is my turn to pray out loud in a group. Everyone else sounds fluent and I sound like an idiot. How do I get past this?

“And Moses said unto the LORD, O my Lord, I am not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I am slow of speech, and of a slow tongue. And the LORD said unto him, Who hath made man's mouth? or who maketh the dumb, or deaf, or the seeing, or the blind? have not I the LORD? Now therefore go, and I will be with thy mouth, and teach thee what thou shalt say.”

Moses is at the burning bush being handed the largest speaking job in Israel's history, and he objects that he is not eloquent and is slow of speech. God does not tell him he is wrong about himself, and does not promise to make him impressive. He points to who made the human mouth and says he will be with it. The commission stands and the self assessment is simply set aside.

“And when they heard that, they lifted up their voice to God with one accord, and said, Lord, thou art God, which hast made heaven, and earth, and the sea, and all that in them is:”

Peter and John have just been arrested, questioned and formally warned by the ruling council. They go back to their friends and the whole group prays out loud together. Luke records the substance of what they said and nothing at all about its style. This was a frightened church in a hostile city, and their instinct was to speak to God in each other's hearing rather than go home and do it alone.