When I was young, I once read a book all about superstition. The only topic from it that stuck with me was about why we say "Bless you" after someone sneezes. The author said it had come from a superstition that our souls could escape or could otherwise be vulnerable to evil forces. Looking back on this now, it appears the author was
not necessarily right. Good ol' Snopes.
Either way, it had a tremendous impact on me. Being a curious child who was taught to think critically about the information I received, I reacted appropriately. "That's ridiculous," I thought. "I don't believe that, so I'm going to stop saying 'Bless you.'" And I did-- from that day on, I never again uttered those words after a sneeze. Even if that isn't the real origin, I still see no reason to bless anybody because of a sneeze. I'm not religious, blessing things has no significance to me. And we don't feel compelled to bless anybody after they cough or vomit or anything. Why the sneeze? Sorry Snopes, but your explanation just isn't good enough to get me to start it up again. Doing something just because we've always done it is a poor reason to continue any irrational practice.
While this superstition is pervasive, it doesn't have an intense psychological effect on anyone, as far as I know. I've never had anyone sneeze, panic, grab me and scream "FOR THE LOVE OF GOD, BLESS ME OR WE'RE BOTH GOING STRAIGHT TO HELL."
There are others that can create serious phobias, with the most well-known being
triskaidekaphobia.