Most times we are talking to someone in our minds. Either to someone or to ourselves. As long as the conversations are pleasant, they are welcome. But there are times when we just want to stop the conversation we are having with a family member, a friend, a stranger etc. This is because the conversation is going around in a loop, the same conversation has been had multiple times and it is wearing us down. Try as we might, we are not able to stop the flow of thoughts.
There are many ways of stopping the thought and here is one. Start giving a running commentary on everything around you. Describe what you see, what you hear, what you smell and what you are touching. Describe everything around you in as much detail as possible. If you are taking a walk, describe to yourself everyone you are seeing, what they are wearing, what they are doing etc. If you are sitting inside your home, describe everything you are seeing, all the sounds that you are hearing, etc. This exercise will force you to be in the present moment. It is difficult to have two conversations in your head and hence will prevent the original disturbing conversation. Do this for five minutes and then with practice you can extend it to a greater amount of time. It can be done anywhere, anytime when you feel the need to stop your thoughts from overwhelming you.