Hi Janejac,
Welcome to the forums and thanks for posting.
Overthinking is a difficult one and something that I struggle with a lot. One of the biggest strategies in managing overthinking is therapy; as thought-challenging can be a great way to gain some perspective and interrupt the pattern. Are you seeing a therapist at the moment? If not I would encourage you to have a look at thought-challenging behaviours just to get a better understanding of how it works.
Other things that can be helpful can include meditations, mindfulness, breathing exercises, colouring (or any creative work) and exercise. I also like to journal and find this incredibly helpful - I liken it to getting the cobwebs out of my head. Making sure that you have a good support group that you can talk to can also be helpful. I also personally like planners and lists - they help me schedule my day and having that structure can help.
At the end of the day though it's about finding what works for you. Different strategies work for different people. Maybe it might be helpful for you to post what sorts of things you've tried. It may also be helpful to see if there's a trigger for your overthinking - what tends to bring it on or what makes it worse/better.
I hope this helps.
