I should be vegan. But I'm not vegan.
At core, I am entirely sympathetic with both the ethical and health-based arguments in favor of a vegan diet.
I'm not even thinking in terms of the animal-cruelty / infliction-of-suffering issues. Those are concerning, but for me, they don't really offer a compelling case in and of themselves, because I suspect that, in the broader scheme of things, suffering on the part of individuals is inevitable – it's a part of existence. Do animals raised for food suffer more than animals in the wild? Yes, certainly, many times – especially in factory farming that is so common nowadays. But animals suffer more in nature, too, sometimes. If we pursue this ethic to it's logical end point, we end up banning carnivorism from nature, and throwing tigers or eagles in prison. Silly.
No, for me, the ethical argument is about sustainability, carbon-footprint, environmental impact. I'm one of those who believes the eliminating meat from the human diet would probably have more impact on global CO2 emissions than eliminating the automobile. Seriously – this is very likely true. If we want to have an environmentally sustainable future, we must, as a species, move toward a sustainable diet, and such a diet really can't include meat for 6~7 billion plus humans.
When I was losing my 60+ pounds (25 kilos) in 2006~2007, I did so, mostly, while consuming a vegan diet. I felt healthier, and it was much easier to keep within the calorie rules I'd set for myself. But several things favored that approach, at that time, including leading an almost entirely solitary lifestyle (not going out with friends, not having an out-of-home job e.g. I was working from home, etc) and living across the street from a very well-stocked and progressive grocery store (the Lunds in Minnapolis's Uptown).
The fact is, however, when it comes to actually practicing veganism, there are two contravening factors: my laziness and my character.
I am stunningly lazy. And being vegan in Korea (where everything you eat, when eating out, in infused with animal product; and where meat-eating is fetishized to an even greater degree than in the US – really!). Also, my laziness affects my ability to resist cravings and habit, too. I have a craving for, and a habit for, things like dairy products, especially. I just simply like them, and not eating them is hard. Kind of like jogging every day is hard. And so, because of my laziness, I don't do it. I buy cheese, and eat it. I keep butter, because I like it. I have tuna, because it's easier than making sure I've complemented my grains and legumes properly in every meal so as to get the right dosage of protein. Laziness.
I am socially a chameleon. I'm timid, in a way. I don't like to "make waves" when socializing with people, and socializing with people is often done over food. I prefer seek out moderation, and seek out the path of least resistance in social situations. And especially in Korea, declaring one can't eat or drink anything (anything!) leads to a lot of difficult excuses, white lies and justifications, for Koreans take near-personal offense if one doesn't eat or drink something on offer. Some in younger generations or who have lived abroad will keep their mouths shut about this, but the offense and confusion, even in those cases, is still there. Trust me.
It's very difficult for Koreans to understand NOT eating something. Perhaps it's the fact that only 2 generations ago, starvation was common, even in South Korea. Starving people rarely make judgments about the suitability of different types of food. And I feel uncomfortable coming across like I'm judging other people, which any declaration of dietary rule-following tends to come across as – it's not my place. Character.
So I'm an opportunitarian. I never buy meat for at home, because I don't actually like meat, so not eating meat is easy for me. But I am unable to kick the dairy-products habit, and I keep eggs and fish, sometimes, too. And when I'm out, I'll eat whatever is given to me: strange Korean things… raw flesh of animals and sea monsters, blood sausages, barely dead creatures, etc. I'm just trying to be polite. It creates a lot of goodwill in my hosts. That goodwill is important.