I do this also. I’ve especially been doing it a lot lately. I figured it was anxiety but your explanation of rumination makes sense. I guess we have to learn to live with it. Like so many things in life we can’t control. I love to read and that tends to interrupt the ruminating thought process for me. Especially a mystery that really holds my attention. Going for a long walk also helps me. Watching TV or movies doesn’t do a thing for me. Journaling helps somewhat because I go back and read it later and see my thoughts more from an outside perspective. I like to journal advice to myself and when I go back and read it I am surprised how right I was. Lol. My brain and emotions won’t listen to my own better judgment. Thanks for bringing up this topic. It’s a good one to contemplate... not ruminate... just contemplate.