Insecurities

I was thinking earlier about insecurities, those little things about yourself you don't like, be it about your appearance or a trait. What I find fascinating is what you personally notice and what other people notice. What I fixate about and truly hate other people haven't even noticed. It's so easy to go around day to day stuck in your own head, picking at every single thing you hate or worry about it. When you think about it logically it's absolutely ridiculous, considering other people don't care/notice the same things. It's interesting considering that nearly everyone has something that they'd change about themselves, how many other people actually even take notice of that same thing?