As a long time "sufferer" of overthinking, I have grown quite familiar with it lol. There is a time and place for Thinking, and it can produce amazing ideas and creativity, such as in writing: thinking is a key component of development. But as with everything, its benefits are not absolute :/ when you pass that threshold into OVERthinking, and sacrifice productivity, it truly can become a problem. I find that for me if I notice I'm falling into that problem mode, one way I fix it is to get away from the physical area(99% of time it's my room). Once I have been away from the area for a while, it somehow resets something and the thoughts don't consume me.

I have no idea why this works for me but it does, so I hope it can help someone else too