What is rumination, and how is it different from thinking a problem through?

Problem-solving moves towards action and eventually stops. Rumination circles the same material without resolution, tends to focus on why questions rather than what-next questions, and typically leaves you feeling worse rather than clearer. A practical test: after twenty minutes, are you closer to a decision or just more upset. Things that help interrupt it: a hard task switch that demands attention, physical activity, writing the loop down so it stops being rehearsed, and scheduling a fixed worry window rather than allowing it all day. Time limits work better than trying to stop thinking about it.