Most things are not about you. It isn't raining to spoil your picnic or parade. It just happens to be raining. A large step in mental health is just to realize that only things about you are really about you. Even then, the incompetent waiter might affect you, but the reasons why he is doing what he is doing are not really about you, personally.
I care about how people perceive me, for pragmatic reasons. But I have somewhat overcome caring about how I am perceived for existential reasons. In other words, it is convenient to be perceived well, because it can bring advantages, but I don't need that approval to bolster my sense of self. I once did. As a consequence, I can just do what I need to do without worrying too much. Ironically, when I did worry in a more existential sense I often made pragmatic mistakes that caused me to be less well regarded.
Once you isolate the things that really are about you, then you have a smaller subset of things to worry about.