I asked the question about worrying as it seems we all have our bouts. I think the trick is to recognize what you can change and the things you can't. If you can see the overall picture from that perspective, you can easily see that some things simply won't benefit from the energy you spend worrying about them. The next logical step is to find ways to use your energy to take care of the things you can influence.
I know there are those times when the outcome of a troubling situation affects your next step and in those times, the best you can do is have a plan for all possible outcomes. I can do this if that happens, and that if this happens. To that end, that's the best you have. Do the best you can with what you have today, make a positive impact and in the end, you will be left with a feeling of satisfaction knowing you took action.