What Terrifies the Ever-Loving BAJEEZUS out of you?

I'm not sure I would call it a "fear" because that implies some level of rationality, but... I'm a claustrophobe, especially with large crowds. It's not like being afraid of something that can legitimately hurt you, like poisonous snakes or falling off your roof. Intellectually, I know that I can't be injured by being in a small, enclosed space. But if I'm in one, I panic; crowded elevators are the worst! It bothers me that I have this visceral reaction to something harmless. It seems to have gotten worse with age.

Cheers,
G