How do I stop overthinking?
You stop overthinking not by forcing yourself to think less, but by giving your mind something finite to do instead of something infinite. Overthinking is not a thought problem. It is a completion problem, your brain circling a decision because it has no signal telling it the decision is done.
What is actually happening
Overthinking feels like your mind refusing to stop, but it is closer to your mind refusing to accept an answer it already gave you. You run the same three scenarios about the email, the conversation, the decision, twenty minutes after you already know what you think. The loop is not searching for new information. It is checking, over and over, for a feeling of certainty that a genuinely uncertain situation is never going to produce. You keep asking the question because the question is unanswerable the way you are asking it, not because you have not tried hard enough.
Why it makes sense
This is not a personality flaw or a discipline failure. If you grew up in a house where the emotional weather changed without warning, or where being wrong cost you something real, scanning ahead for every possible bad outcome was a genuinely useful skill. Your nervous system learned that stopping to think one more time was cheaper than getting blindsided. Overthinking is often just vigilance that never got the memo that the threat level changed. You are not broken. You are running a very old and very reasonable program in a context where it no longer pays off.
What actually helps
Trying to stop thinking about something keeps it active, the same way trying not to picture a red door keeps the door in the room. What works instead is narrowing the question until it has an edge. Not 'should I take this job' but 'what would I need to be true by Friday to say yes.' Set an actual endpoint, a specific time you will decide by, and tell one other person what it is, out loud. A deadline you have said to someone else functions differently in your head than one you only thought. Writing the loop down by hand also helps more than typing it, because handwriting is slower and forces the thought to finish a sentence instead of looping mid-thought. The goal is not calm. The goal is a stopping point your mind will actually recognize as real.
When it is something else
Sometimes what looks like overthinking is actually your gut already knowing the answer and your mind stalling because it does not like that answer. If you notice the loop always lands near the same conclusion before you argue yourself back out of it, that is worth paying attention to on its own. Overthinking that resolves once you finally admit what you already suspected is not really overthinking. It is avoidance wearing analysis as a costume.
When this runs your life, it usually traces to one underlying pattern. For this, it is most often the Mirror rhythm, the thing under the behavior.