You have all heard the title statement before, but have you ever really looked at how it plays out in your own life? I can allow myself to get all worked up over a horse show competition, making gravy for turkey dinner or even getting to an appointment on time. If I really stop myself and rationally examine each one, I can see that none ars really worthy all the anxiety. But you might say performing a certain surgery at work or giving a critical presentation to the firms oldest client - these are truely worth getting excited over. When I worked as a surgeon, I took my work and my patients trust in me very seriously. But one day I sudddenly ended up in the hospital. Patient care continued and the quality did not slip. All my worry was for naught.
Preparation for possible outcomes, even failures is not a waste of time. You might even learn something to prevent tragedy later on.