Wow, I had no idea he was so into the vegan lifestyle. Decades? I couldn't do it; I love a good steak!
My friend went vegetarian about a year ago, she didn't have to many problems with it. Vegan on the other hand, that takes a lot of commitment and control (not that vegetarianism doesn't). With both, you have to make sure you're getting all your essential nutrients and vitamins.
A year or two ago I decided not to consume dairy anymore. It was hardest thing I've ever done. I thought I was going to go crazy I eventually had to modify that a bit, because I just couldn't live without ice cream, cheese, and bread. Especially the ice cream