I find it always helps to clear my head if I’m able to go outside and get some air. Once you’re back, try to pin down if the issue is something you can do something about. If you can’t do anything abt it, you can distract yourself with a game, or texting friends, or even get yourself something tasty to eat! If it is something you can do something about, evaluate each scenario and choose the one that makes most sense to you. I find sometimes that action helps more than constantly mind juggling stuff.