I was a vegetarian for about 6-7 years, but about 6 months ago or so I started eating fish again. I still don't eat beef/chicken/pork, just fish... My girlfriend is basically the same, though she eats even less fish than I do.
I have several friends that are vegetarian or vegan (for some reason, the electronic music scene is full of veggie people), and even those that AREN'T mostly eat pretty healthy, which all makes it a lot easier to avoid unpleasant situations like the one described in the first post.
I stopped eating meat as a reaction to the fact that I was eating way, way too much meat. Every meal had meat, and some meals were JUST meat. There's a lot of history of lifestyle-related illness (heart disease & digestive tract cancers) in my family, and I made the switch in a sort of fear-based desire to eat healthier after several of my older relatives dropped dead prematurely due to problems their doctors felt could have been prevented with better diet and exercise.
If that had been all there was to it, I probably would have drifted back to my carnivorous ways pretty quickly, since these sort of panic reactions tend to subside right away. But what I noticed was that I felt a lot better, sort of "lighter" (not just weight-loss related, but there was some of that). I felt much less tired & lethargic after meals, more clear-headed and energetic. I didn't feel stuffed full for as long after eating. I felt like my body "liked" the new diet better. For a while I missed steaks & stuff, but I felt so much better that I wasn't willing to go back.
I know some "moral" vegetarians who think killing animals is wrong, and I don't really feel that way, though I do have some problems with certain aspects of factory farming. I think the meat & dairy industry has some real problems with overuse of chemicals, both hormones and anti-biotics, but you can avoid both these things by buying organic milk, for example. Still, my dietary choices have zero to do with the whole "it's wrong to kill an animal" argument. I still wear leather sometimes.
After a while of not eating animal flesh, you DO start to think about it differently. It starts to seem less like "food" and more like "dead body" when you look at meat on a plate. This change in perspective has diminished a bit, so that I can eat fish without feeling "yick, dead flesh" about it.
In a very real way, I think of my conversion from "meat eater" to "vegetarian" as being similar to my conversion from "Windows zealot" to "Mac enthusiast." In fact, both changes happened at around the same time, though the first was sudden and the other was gradual (and ongoing). But I feel that many Windows users just use Windows because that's what they were brought up doing, that's what their friends or family or teachers or co-workers did, and they don't question it. They think there's something kooky and a little pathetic about Mac users.
It's the same way with meat eaters and their unquestioning assumption that "of course humans are meant to eat meat, because they always have, and they wouldn't have such sharp teeth if they were meant to be herbivores." Meat eaters assume that vegetarians are kooky and slightly pathetic, in general, too.
There are further similarities in that these assumptions are based on misinformation. Most meat-eaters assume that vegetarians eat nothing but salads and little plates of apple slices, and don't really enjoy their food. But if you meet and hang around with a "real" vegetarian you'll find that they (we) have a real love of food, and enjoy a really diverse diet. I remember going to a CD release party in Bellingham Washington -- one of my electronic music buddies and his wife were vegans, and they & all their B-ham hippy friends made an amazing vegan feast. This really opened my eyes that you can have a really exciting, varied, tasty diet without meat, and even without eggs/dairy (though I wouldn't or couldn't make this last change myself).
I eat all kinds of really great Asian food, especially Thai food, various kinds of pizza, and tons of Mexican food. There are lots of options, many great restaurants even in a mid-sized city like Portland, and (especially since I started eating fish again sometimes) very rarely do I ever wish I had more restaurants or dishes to choose from.
When a meat eater acts condescending about my dietary choices, I feel exactly the way I do when a PC zealot acts condescending about my use of a Mac. I want to say "I've been there, brotha. I've been where you are, so I understand your side, and I'm telling you there's another way!"
The funny thing is, a year before I "switched" if you'd asked me if I'd ever change, I would've said "No way, never." But in both cases (quitting meat and getting involved with the Mac) I ended up surprising myself by changing, and being happy I did.