I totally relate, as an overthinker myself. I recently installed an app which helped me a lot with this issue. It's called "What's up". It's full of tools you can learn and apply in any moment. They require five minutes or less. They'll help you bring yourself back to the present moment. Because when we're overthinking we're stuck in our head. 'll make you an example of what you can do: 1. noticing and saying 5 things you can see, smell, hear, touch. There are so many more exercises you can try; you'll learn them in this app if you feel like installing it. I hope I have been of some help :)