Yuck!
Well...what do you believe are your greatest strengths? Are you particularly interested or involved in any activities, or have you developed certain skills (leadership, etc.) that could carry over into and influence your medical school years?
These questions are always so uncomfortable, aren't they? Right up there with, "Why should we choose you over other candidates?" Generates all of that anxiety about walking the unsteady line between confidence and narcissism!
If I were in that situation Barin, I would really just be honest, and make sure that I backed up everything I said with examples of some sort. I think unsubstantiated claims might appear hollow or arrogant...but if you provide specific points, and support them with things you've done/ experiences you've had/ things you've learned not only about medicine, but about life in general...then I'd imagine you'd be in good shape.
Although, who the heck am I to know????