I mean, conditioning. The first time you swim is fucking terrifying, but once you realize it's not that hard to not drown in still water, it's not that scary.

But this isn't really a universal law - hunger and food, for example. I get intensely hungry every day and feel the same intense relief. It never ends. I get the same intense anxiety in new social situations every single time, and I have to do that a lot at my job. I also used to be a heroin addict and I got the same intense sickness and the same intense high, as long as I could afford it, every day.

I think the real answer is just the concept of "normal."