As is said, worry is a misuse of imagination (Dan Zadra). What starts as a single concern can quickly escalate. Before you know it, you are caught in the undercurrent of cascading thoughts.
It is worry’s duty to confront you with the enormity of the worst case scenario. However, you need not go for the ride. Whenever overwhelm hits, bring it back to the moment at hand. Your power cannot be found when your attention is scattered amongst the many (erroneous) stories your mind is telling you. You can choose to get ahead of yourself or get a hold of yourself.