I live in almost constant fear of being judged. It's the underlying source of most of my anxiety. I used to think of it as "reverse narcissism": when I walked into a room, I was completely sure that I was immediately the center of attention, but all of that attention was negative. I knew, logically, that that wasn't true, but it felt true.
However, I just realized that, once I know I've been judged, my anxiety dissipates. Not immediately, but slowly, over time, it wears away. And this works even if the judgement is negative. In fact, my go-to examples of this are of negative judgement.
My favorite example: I was in a class that was a requirement for a lot of majors. I was just taking it to get some credits and because it sounded interesting, but the vast majority of my classmates were just there to fulfill the requirement and didn't bother to hide it. They had so little respect for the class, the subject matter, as well as poorly-hidden boredom for our very nice teacher. I hated those fuckers. I seriously wanted to smack most of my classmates upside the head with the textbook.
So when we had to do group presentations in front of the class, I didn't even sweat it. Seriously, I have never been less nervous doing public speaking in my entire life. When it was my turn to present my part of the project, I walked around the front of that classroom like I OWNED it. I swept my eyes over the entire class as I talked, and aside from occasional glances at my notes, I came off as if I had a deep and intimate knowledge of the subject matter. Ice cream would've envied my cool. The teacher was blown away (and my grade on that project and in that class reflected it).
And it was all because I gave not two shits what those little assholes thought of me. Because I'd seen them roll their eyes at me, because I watched them avoid me, and because they pissed me off with their complete and utter disrespect. (The course was "Communication & Culture" and it was basically ethnography 101. The whole course was about learning to see things through the eyes of people whose cultures and experiences are different from yours, and these entitled little brats missed that point entirely, which is pretty bad considering it's the main point of the entire fucking class.)
And I get that reaction, I do (meaning my reaction to being judged by the snots), but I just never took it up a level and looked at it through a larger lens. It's the not knowing what people think of me that gets me anxious, but once I know, even if they do think I'm stupid/fat/lazy/whatever, then I can adjust how to react to them.