What you do is who you are. How else could one be identified. I guess it's possible to define something by what it's not (something is dry if it is not wet...).
When I identify myself, it's always with something that I do. I'll tell you that I'm a runner (I'm starting to say triathlete), a student, a nice guy, a low-grade adventure seeker, an economist, or a chemist (usually chemist is in the past tense). I don't say that I'm white. I was born white and there's nothing I can do to change that. It's not something that I do. I am an environmentalist, but not the militant kind. That's because I do the 3Rs, ride my bike for transportation when possible, buy recycled, etc. but I don't chain myself to trees or live in a tree. I don't normally say that I'm a man or an American...once again, those are things that are either obvious or irrelevant.
When I try to identify other people, I identify them by what they do. They might be partiers or dancers, mechanics or video-gamers, impulsive or cool, birdwatchers or knitters, slackers or gangsters. I would like other people to evaluate me based on the merits of what I do.