All fears are irrational to a certain degree.

If you put a snake next to someone, and tell them it’s harmless, and they don’t need to be scared, it doesn’t mean they can just switch the fear off. Fear resides in our primitive brain, in our limbic system, and our fight or flight response is hard-wired in. It’s hard to override that even with rational thoughts.

Which is why I was surprised to discover I’ve developed a mild fear of being ill.