All of those great reasons aside, these are my main reasons:
Because I love my furry beasts so much it hurts, and I cannot stand for a moment imagining what it would be like if they were mistreated, used and slaughtered for human consumption, I am vegan.
Because I am an intelligent human being who can make decisions based on ethics and morals and am not required to do things just because my ancestors did, I am vegan.
Because cows are rad, pigs are awesome, chickens are great, fish are amazing, sheep are gorgeous, bees are necessary, I am vegan.
Because my ethics are more important than convenience, I am vegan.
Vegans: What motivates you and keeps you going in a world which would much rather you just homogenize yourself, stop being a pain in the ass and just eat some damn bacon already?