When you have taken all the action there is to do, thinking positive thoughts is the most productive action you can take. There is no positive benefit to worrying. If I spend all my time thinking positive thoughts and disaster comes anyway, I would have wasted my time. Positive thoughts create healing, produce enjoyable emotions, and reduce the stress in your life. Positive thought stimulates you to look for solutions to your situation and increases the energy you have to take action.
Positive thought makes the journey worthwhile no matter what the outcome.
Someone once asked Patricia Sun, a spiritual teacher, what would happen when she died and found out she was wrong about the philosophy of joy she was teaching. If I don't worry, I won't be prepared for the worst possible scenario. If the worst possible scenario does happen, you will have plenty of time to be upset when it arrives. Spending months in anxiety does not prepare you for anything. You can not pre-experience emotions caused by a disaster.