Also called Rumination, it is not a mental illness but is associated with other disorders such as depression, anxiety, eating & substance use disorders.
If you are suffering from overthinking or know someone who might be overthinking,, here are some of the ways you can stop it!
Identify the thoughts and patterns that make you overthink in the first place.
You don't have to believe in everything that comes to your mind. Sit calmly & filter out the negative thoughts.
It can be difficult at first but meditation can help calm your racing mind & also to retrain your brain.
Journaling is a great way to clear your mind. Use it to remove all negative ones & empty your head of the clutter.
Exercise has huge physical & mental benefits. One of those is getting rid of overthinking.
Get social and talk it out with your friends. Get some insight into it with a trusted friend(s).
If you have tried all the other ways & still not getting anywhere, seek some medical help to get it sorted out!