" The longing for certainty is in every human mind… but certainty is generally an illusion."

by Oliver Wendell Homes

How do you support yourself when doubt and uncertainty enter your mind? One strategy is to clarify the worst possible outcome, determine how you would handle it, and then remind yourself that this outcome is also unlikely, (but if it does happen, you are prepared). Many strategies work.  What is important is to have a strategy that works for you.