Obsession and rumination are things that we all do to a certain extent. Obsessions tend to be recurrent worries about the future. Ruminating is about the past, and our real or perceived mistakes and failures.
Obsessions and ruminations are not typically helpful, and when experienced as out of control, can be really upsetting. They are also ineffective in terms of solving problems and feeling better, as they tend to trap us in a cycle of anxiety and powerlessness. Thankfully, therapy can be very effective in helping people who really struggle with obsessions and ruminations.
This video clip from Buzzfeed provides a very irreverent look into the mind of someone who obsesses and ruminates. Any of it sound familiar?