just be natural and discuss subjects you are passionate about and maybe discuss volunteer you have done. For one of my interviews, they asked me what the hardest moment in my life was and I got emotional because I come from a rough area and there were a few things that came to mind but I spoke about losing a close friend and how it made me stronger, the important thing when they ask any question like that is to show how you’ve grown as a person because of an experience. Also colleges want to make sure students are multifaceted so the more you can show that, the better. Good luck 
Please feel free to answer my question
http://talk.collegeconfidential.com/college-admissions/1740097-can-someone-help-me-edit-this-essay.html#latest