Never ending
People who overthink have the habit of worrying over things they have no control over, and are often dwelling on past events or reminding themselves of little mistakes they did. The first way to stop overthinking is to ground yourself in the present moment. Try unplugging yourself away from the screen, eat mindfully, or go outside and take a walk.
The feeling of repetition and being overtaken by thoughts is animated in CSS using a fifteen-frame sprite sheet.