My day job in Human Resources requires me to classify positions for employees in the organization where I work. It's a tough job because it impacts employee titles and salaries. Conversations can become heavy with tears of joy or angry rants, depending on the outcome of the classification. Personally, I believe this is because - duh - it involves money, but also because most people define themselves by their job.
What's one of the first questions you ask someone you meet? It's usually "Where do you work?" or "What do you do for a living?"
Most people will tell you that they are a title - mom, wife, engineer, teacher, marketing rep, father, etc - but these are reflections of our external world, a condition of existence within a larger perspective.
My other job as a writer requires me to create characters by focusing on the internal. When defining a character, I think more about personality traits and personal goals. Cassie, my main character in Entangled, is curious, empathetic, and a little dissatisfied with her current life. She's also loyal and funny. These traits define her more than the fact that she is a teacher, a Texan, and a divorcee, because they determine her actions.
Character is action. We are what we do.
So if someone were to look at you and say "Tell me about yourself," what would you say? How do you define yourself to a stranger? How do you define yourself when you look in the mirror? How do your titles, your actions, and your thoughts and feelings impact the way you perceive your reflection?