How to stop overthinking

Maybe react counterintuitively to it.  For example from now on when I notice I am overthinking I am going to say ‘thank you’ in the same way that I might be kind encouraging and polite to someone trying to do their best for me.  ‘Overthinking’ doesn’t mean any harm; it’s just desperate to help, the poor thing. It started billions of years ago and it’s been practising since then to help keep my ancestors and me alive. 

Be aware of it. Be so completely aware at all times so that you see the patterns that you fall into. Don’t try to do anything about it or try to think your way out of it. Just be curious and observe so that you catch the first thought that starts you on the snowballing. And if you aren’t able to catch it straight away that kind of observation will help you to catch when it went too far so that you can bring yourself back to “zero”. Don’t judge yourself or condemn yourself. And don’t be afraid of anxiety. Just give your full attention all the time. And if it goes too far and the anxiety gets bad once you realise that your train of thought led you to negative feelings and you’re clear about that intellectually, turn and face the feelings. Quiet down your thoughts to stop the train (which will happen automatically if you really see how it happened) and turn and face the feeling of anxiety like a warrior establishing dominance over a predator. That’s what works for me. I don’t worry about “a look” or “change in subtle behaviour” anymore. I still have anxiety but it’s mainly brought on by my children. A parent always worries. 

I think there's no magic answer. I do find tegular meditation practice helps you become more aware. So that when you do realise you are overthinking you can distract yourself. Also that one looping thought about the little things can shout just as loudly as the more significant things. This tells me it's "simply" a matter of attention. If you can divert it, it helps. Sometimes I need outside influence to divert it as trying myself doesn't always work.

People are difficult because by their very nature they are unpredictable. I have to deduce and work out that things or sutuations are ok.

Fighting overthinking empowers it.  I recently said to my overthinking ‘I surrender; you win’.

https://www.youtube.com/watch?v=qtMFov8jCqE



OK now for the serious answer:

It's very difficult to stop the runaway train of thought sometimes and although CBT is not the best for everyone, I will say in the book I had accompanying my sessions I found the passage about breaking out of spirals helpful, especially regarding what's called catastrophising.
I'm not able to photograph the page for legal reasons but this article is the next best thing I found to explain catastrophisng (the use of positive self talk also applies to other anxiety worries)
https://positivepsychology.com/catastrophizing/
from my own experience replacing the negative pattern with a positive or at least neutral one takes time there's quite a bit of "fake it 'til you make it" as it takes several weeks to start forming a new habit. Hopefully that's helpful to you.

Transcendental Meditation, works a treat

Much the same for me, 

the thoughts are real, but try to remember often not true.

I can loose day after day.

I dont have many solutions but I think you are among a lot of people who struggle with that too here! I have done my whole life and yet to find a solution 

That helps me too. Sometimes I remind myself that the things that are going on in my head are not necessarily real and that seems to help 

Problem-solve one thing at a time. List some anxieties and internal conflicts and let’s see if they’re an easy fix! Some are and some are more complex. Some might be intensified by other unresolved issues. 

over thinking is a term used by non-autistic humans who ruminate without resolve. But we don’t tend toward worrying about issues we cannot fix. 

Honestly, I don't know, but I can tell you that you are certainly not alone in this.  

Sometimes it helps me to write things down.  Sometimes it helps to remind myself that I am seeing things from a skewed perspective.  But the loop carries on anyway.