This one is really hard to combat. The overthinking brain imagines every scenario ever, really hard to tune the noise down. I've gotten better at it lately but it's still difficult sometimes.
A technique that can be very effective at breaking patterns of cognition is to every time you find yourself doing it, name it and let it go. Don't try to resist or get angry or attach any emotion to it, just say "I'm just simulating a discussion" and drop it.
Doesn't matter how many times you have to do it in the beginning, every 30 seconds, whatever, as long as you persist in doing this, it will relatively quickly stop the thinking pattern.
This one is really hard to combat. The overthinking brain imagines every scenario ever, really hard to tune the noise down. I've gotten better at it lately but it's still difficult sometimes.