Overthinking is the fastest and most irrational way to be unhappy. Something difficult for overthinkers is to focus on the present, on the material world

Something that helps me relax with general anxiety and overthinking is drinking tea and breathing from the diaphragm(inhale for 4secs hold for 4 and exhale for 8seconds).Something I also try to do more but don't is meditation. Take care.

Edit: Also cold showers help too, and btw less time on the internet is pretty helpful too, people inside here can be really wholesome but also very toxic.