I became vegetarian 30 years ago after reading a book that laid out a reasoned argument for vegetarianism based on concerns for animals, personal health, and sustaining the environment and planet as a whole. As Mommawolf says, it's a personal decision and one that I've never tried to foist on anyone else.
If someone asks me "why" I'm vegetarian, etc., I explain. I buy canvas shoes and purses, non-leather boots, etc. and just go by whatever the current descriptor is for them - faux leather/fur, pleather, whatever. I wish more people considered the plight of animals but that's just a wish not a critique. It's hard when you feel strongly about something not to make a case for it, but I want to point out that conviction and judgement are two completely different things.