This may sound silly but I have no idea how to even start an essay that asks to describe yourself. Am I the only one? I can't imagine I'm the only one that has issues writing about themselves in that manner. Any advice?
what is one thing or theme of your life you want people to know you by? center your essay around that and tell how that came to be.
i.e. You may want someone to know of your interest in sports and how that translate to your life. how you came to like sports, how has sports defined you, what you plan on doing to integrate sports with medicine...etc
I definitely would focus on something not covered in your PS, primary app, or other parts of the secondary app. Pick something unique about you and use it to describe parts of you. Pick an experience, aspect of your life, something you value, etc. and work off that.
For mine I talked a little bit about how my family was important to me. This transitioned into how I came to learn about caring for other people, building relationships and that transitioned into why I wanted to be a doctor.