I've been naturally shifting towards a more plant-based diet over the past few years as a result of being heavily involved in environmental coursework and research (the "how the sausage is made" effect, if you will). I stopped eating red meat three years ago after learning how inefficient and carbon-intensive beef production is. I stopped eating shellfish two years ago after a research project where I learned about the destructive ecological consequences of shrimp aquaculture and the widespread use of slave labor...
From Brown to Green 