I was vegetarian for years and then when I was at a health food shop I saw an advert saying if you are vegetarian you need to watch this. I watched it thinking it was going to confirm that by being vegetarian I was doing the right thing. I was shocked at how naive I had been regarding the dairy industry and a lot about this article (link below) sums up my thoughts before and after realising that giving up meat is just not enough. It was that video that made me become vegan and to this day I cannot even think about what I saw in that video over three years ago.
(Below is an article about how giving up meat is not enough, not the video I saw)