Rumination

In psychology, rumination is when you can't take your mind off of something, often a bitter or negative experience you had in the past, and it still continues to bother you. You try to combat these intrusive thoughts, but they keep coming back no matter how hard you try to push them out. Rumination can be anywhere from a few minutes to an entire hour. This is often due to a lack of resolution/rectification towards the bitter experience, especially if you failed to take control of the situation. Rumination can also be about future events or goals, especially a harmful, unhealthy and unrealistic goal that you want to pursue. The more you ruminate, the deeper the hole you're digging for yourself. It is better to stop ruminating early, or else you might end up in a very unhealthy state, both mentally and physically.