I've been vegetarian practically my whole life. My mother says i would literally not open my mouth every time she tried to feed me meat or something with meat in it. Luckily, she eventually gave up :)
I occasionally used to eat only minced meat (like meat balls, burgers etc.), because it had totally different structure and taste, and i kind of didn't associated it with whole piece of meat, because it didn't make me through up, i didn't have the gag reflex from minced meat. And for years the minced meat was my defense against the judgmental comments from people who eat meat.
It was last year, 2013, after reading a story about guy being a vegetarian his whole life, when i realized that it's not just the taste and the structure that makes me sick, it's the thought of putting something dead in my mouth too. The mental switch after that was fast and easy, minced meat and just meat are 2 sides of the same coin. And i stopped care about other people's comments, about the society's "good advises" on eating meat, i stopped explaining my self.