Sometimes the best thing you can do is not think, not wonder and not obsess. Just breathe and have faith that everything will work out for the best.
There are two things that you can do in tough situations. Either you can worry about them, or you can pray. It really is hard to do both, because when you do one, you are showing that you believe in it. If you show that are worried, you show that you believe that there is a chance that the worst possible scenario will play out. When you pray, and when you don't obsess, you show that you believe Gods word, and what he said.