My best trick to do this is to visualize a camera in the room with me, like some director is putting this scene into a movie. Try it out right now, visualize what you'd look like if this moment was a scene in a TV show. Maybe I get a precious glimpse of how I appear to others. I get a different perspective on my automatic reactions, because I'm not inside of them.
I've been studying body image disorders lately. What begins as healthy self awareness can lead to all kinds of problems when you cannot turn it off any more. Having to think all the time how you present yourself to the outside can be debilitating.
I get you are not advocating for that, but do realize the same problem can be approached from multiple directions.