I recently stumbled upon an interesting review by Watkins on the constructive and unconstructive consequences of repetitive thought (RT). He mentions a number of thought processes involved in this concept refined by Segerstrom in 2003 including rumination, worry, perseverative cognition, cognitive and emotional processing, counterfactual thinking, mind wandering, defensive pessimism, and habitual negative self-thinking.
His review of the research literature reveals that the main constructive consequences of RT are recovery from trauma and the ability to plan ahead while the unconstructive consequences are depression and anxiety. Three main factors seem to determine the consequences of your RT; the valence or emotional value of the thought content, the interpersonal and situational context in which you are in while having the RT, and the construal level or perception of the RT.
And here I thought RT was always a bad thing...
You can find the full text here.
Watkins ER (2008). Constructive and unconstructive repetitive thought. Psychological bulletin, 134 (2), 163-206 PMID: 18298268