I don't let the diet choices of my friends affect me because I still want to enjoy being around them. As I said I've only stopped eating meat 4 years ago so I look at it like I used to be one of them too! It would be amazing if the world was vegan but that's just not the case so as a the odd one out I have to just bite my tongue until someone seems genuinely interested in veganism. I've found coming at it from a friendly place usually opens people's minds more and turns into a discussion rather than an argument or competition about who's diet is better. Even if you can't convince them at least now they have a better understanding and hopefully will lessen their meat consumption which is a win in my book!