In my own experience, it was a walk in the park to first give up veal years ago, as soon as I learned about the veal industry. Pork---never liked pork except bacon, so that was easy to give up. Never liked chicken much, either, and even when I was eating it, I'd gag as I prepared it. WTF, right? Why keep eating stuff that makes you sick to your stomach as you cook it? Lamb---never really liked it. Fish was easy to give up because I am an oceanophile and almost fanatically devoted to its conservation as well as to the protection of its creatures (this goes for freshwater ecosystems as well).
Steak and burgers---that was a bit more challenging, as I loved me a bit of steak with Bearnaise. But it, too, went bye-bye.
The hardest was giving up cheese and butter and cheese and ice cream and sour cream and cheese and cream sauces and cream cheese and cheese. LOL. Never liked milk, and it always affected me badly anyway. I was never an egg fan, and hated them unless they were baked into a cake, etc.
Imagine my surprise when Dr. Neal Barnard of PCRM let slip that cheese and butter and other dairy products are addicting. Until then, I had had more success in permanently quitting a 4-pack a day menthol cigarette habit than I had quitting dairy!