Why Can't I Worry About Normal Things?

I stress myself out about the stupidest possible things. I honestly don't worry at all about things that most people worry about. For instance, I have absolutely no concern whatsoever for my own personal safety. Nor do I ever worry about anything I own being stolen (partly because I don't own anything that anyone else would ever want). You know that cliche about people worrying that they left something on and their house will burn down while they're gone? I don't do that. You know how sometimes people get all nervous when they have to be out alone at night, because they feel like they are more vulnerable? Not me. I do however freak out every time I change anything about my daily workout because I'm afraid it won't be as effective as whatever it was I was doing before. What the fuck is wrong with me?