Worry is different than concern. Worry and concern might start with the same intention, it is a much different action. When you concerned, and you do nothing about it, then concern turns into worry.
Worry is thinking the something bad is going to happen over and over and over again. A coward dies a thousand deaths, and every time you worry, you are creating a scenario where what you worry about has happened.
If you have a concern, do something about it, even if all you can do is send good vibrations or prayer. Then you have to let it go and trust that the best is going to happen. If the worst is going to happen, let the worst happen once.