In an earlier post I said that when other people told me I worried too much I used to think they were right, and get, well, worried. And that now I get annoyed instead, which is an improvement. Nowadays I think about it in terms of how I work. As I said in that post, I know I do best when I have a conceptual framework. That means that I have a kind of mental scaffolding for understanding a situation; I know where to put my thoughts if that makes any sense. So when I think about "worry" and "overthinking," nowadays I think of it more in terms of disaster preparedness.
A couple of years ago, when avian flu was bigtime in the news, I had a bunch of conversations with people about preparing for epidemics / pandemics. Would I have the supplies to hunker down and stay safe? What does that involve? Same with Katrina, got us all thinking about what you would do if you had to evacuate suddenly. These are scary things to think about. I noticed that some people (like the one I live with) thinks that it's kind of overkill to be concerned, or to go through a checklist and buy supplies for these kinds of situations. It can be seen as just overactive worrying if you don't live in active earthquake/flood/fire area, for example. But for others of us, getting prepared is something productive and constructive to do with our concerns. It is a way of taking care of ourselves, not by letting anxiety rule us, but by getting our houses in order.
And once that's done, worry is free to subside. In fact for me, I don't even have to carry out a full preparedness plan; merely understanding what it involves and having a tangible sense of those steps allows me to feel more in charge. You could say that the preparedness information is my conceptual framework. If the proverbial -or actual- dam breaks, I'll be mentally ready; so in the meantime I don't have to be concerned, whether or not I'm thinking about it.