I do the exact thing nearly constant. My mind is so busy ruminating about every conceivable thing that there isn't even room left to focus on anything. It's not really an OCD thing. Nearly every Depression sufferer I've ever talked to ruminates. Even if not about any particular event, then I will ruminate about my scenarios regarding my Depression itself. It just sucks the mental energy out of me so badly. Ahhh... How I long for the days when I was just simply in the NOW. Just in that beautiful place where I just did fun and productive things and never gave them much over thinking. Wishful thinking because no amount of meditation for me will halt what my brain wants to do. My mind just has a mind of it's own that's way out of my power to control.