Addendum: I could, in all honesty, actually do just fine on a vegetarian diet. I couldn't do a vegan diet, though. I tried doing a vegan diet myself about four years back when I went all serious-business about getting healthy. Thought it'd make me feel better. All it did was make me feel lethargic, empty, and cranky. I felt, health-wise, better, but mood-wise, I felt like a dead, cranky, humorless husk. I found no joy in trying to convince myself that tofu could taste decent. I'm a very good cook, if I do say so myself; I can make something mind-blowing from the cheapest ingredients; quality need not go in, but quality does come out. I tried cooking tofu and using it in a variety of dishes, trying to make it taste like something other than unwashed socks. All it ended up tasting like was whatever I had added to it. The flavor was bland, and the texture made it feel like it was oozing down my throat. Vegetables and fruits are all fine and can taste very good, and not to toot my own horn again but I can make them taste really damn good. Chive and garlic butter, poured over steamed asparagus, broccoli, and carrots, for example, with a hollandaise dipping sauce [suddenly doesn't become vegan; you see my problem already]. But, see, that's the problem. Margarine can be used, sure, but the flavor is much different, especially when melted and simmered with herbs, spices, etc, than butter, as its consistency. No matter how hard you try, the flavor of butter just is not capable of being replaced when its flavor needs to be directed. There's things you can replace with margarine, but even then, the taste and consistency changes, and not in ways I consider to be improvements.
I'd also never be able to give up seafood. Ever. Crab, lobster, oysters, salmon...they're all way too good to give up.
I'd also never be able to give up seafood. Ever. Crab, lobster, oysters, salmon...they're all way too good to give up.