I have a tendency to overthink things. If there is someone I need to talk to about an issue or if there is a conversation I need to have, I have "mental rehearsals" on what I should say.
Jesus warned His disciples in not worrying about what to say when they opened their mouths to speak the Gospel because it would not be them speaking but the Holy Spirit within them. Mark 13:11 says, "Now when they take you to court and put you under arrest, do not be anxious beforehand about what you are to say nor meditate about it; but say whatever is given you in that hour and at the moment, for it is not you who will be speaking, but the Holy Spirit."
Jesus was telling his disciples that when they went out into the world to preach the Gospel, as He was commanding them to do, they would run into opposition. He was preparing them to face persecution. He was telling them that they would be brought before governors and kings for His sake as a testimony to them.
How many times have you mentally rehearsed what you are going to say to someone? I usually imagine what I will say, then I try to figure out what they will say back to me. In my head, those conversations can play over and over again. If we are filled with anxiety, it may be a sign we think the outcome of that conversation depends upon us and our ability rather than upon the Holy Spirit and His ability.
If we are sure we are operating in obedience to God's will, we don't need to be anxious, worried or nervous about what we are going to say to others. Sure, we need to be prepared, but if we excessively rehearse the conversation over and over, it is an indication we are not trusting in the anointing of God but in ourselves. We will not do as well as if we were depending completely upon God.
Next time we find ourselves in this situation, we need to ask the Lord to give us favor with all those to whom we speak. Then we can be confident that whatever the results of our conversation or confrontation, it is the will of God and it will work for the best for all concerned.