I've been vegetarian since college so about 15 years or so (wow, has it really been that long?). I grew up in the country and my family raised a little bit of everything - chickens, geese, lambs, rabbits, etc. And I raised pigs in 4-H so I had a lot pets that I knew would one day end up on the dinner plate. I was fine with that as a kid, but when I got into college, the guilt started to eat at me (also dining hall meat wasn't that appetizing). And I realized that I didn't need to kill animals in order to live - that was a huge revelation for me! I think it was in the middle of my freshman year that I decided to try not eating meat, and since then I haven't looked back. When I became vegetarian, I almost immediately felt better - both spiritually and physically. Also, almost immediately after cutting out meat, my acne cleared up - a very important development for a 19-year-old college student!
I am still the only vegetarian in my family, which still causes some friction. My one rule is that no meat can be cooked in my house (I can't stand the smell at this point), so if I am having guests, if they want to eat meat, they can get it at a restuarant.