Vegan, in a strict sense, means not to consume any animal products (these include meat, dairy food, honey, bee wax, etc.). I'm trying to be a "practical" vegan, which means I don't want to make my being vegan an issue with people I associate. When eating outside with friends, I normally will not tell anybody that I'm a vegan. Maybe I'll say I'm a vegetarian, but certainly I will NOT refuse eating with people who are not vegan or even vegetarian. I will order whatever food close to vegan, otherwise, I can always eat the vegie part in the meals available (including sharing others' dishes). However, when I'm alone, I try to live a vegan life. Why? Because I believe that being vegan is not merely what you eat or eat not. It's the attitude or motivation, and it is more about mindfulness.
My motivation of choosing vegan diet is NOT merely for health. I often tell people that being vegetarian (or vegan) does not necessarily mean being healthy. You can eat non-dairy candy and cookies everyday not violating vegan rules but ended up with a bad health; and if the luster of body or weight-lose is your only motivation to be vegan, then I warn you that there is NO guarantee!
My motivation to be vegan or vegetarian is compassion and mindfulness. That's it. Of course, trying to be healthy is definitely my goal of life. But that is not the only thing, and there is a danger of getting obsessed with that. There is a huge body of information explaining the benefits of veganism, but it's up to the individual to devour or to digest.