I also tend toward this -- no sense obsessing over something unless you can't do anything about it, right? The only thing that I have found that works is walking or running, *outside*. After my stepdad died, there were nights I'd wake up at 2 or 3 AM and my brain was looping so fast I couldn't get back to sleep, and I'd finally get up at 4 or 5 and just walk, for like an hour or two, until my chest loosened up and I could breathe and my brain settled down.
Of course, when I'm in that fret mode, the last thing I want to do is get up and leave the house. But if I can make myself do it, it helps, every time.