It's true that overthinking is bad but these days just normal thinking can land you in an empty pit. To stay sane we need to think less and only think when we need to. I just concentrate on what I am doing and then I set time aside for leisure, I play computer games.
When I was a young man I watched the movie body snatchers, in the movie humans were being replaced by imitation beings that bear their appearance. The replacement beings had no feelings and were very robotic. I feel like there is an element of that in our society now. People are slowly being turned into psychopaths, if someone annoys them, they will try to get them fired from their job. They would ruin someones life because they are spiteful and find something annoying about the person.