The interviewer wants to get to know you, but they are most interested in information that is relevant to this position. Sharing your educational background, your interest in the mental health field and a few hobbies is a great place to start. When talking about hobbies, think about the ones that could be relevant to the job. You'll be working a lot of people, so if you volunteer or serve on the PTA committee they might be good examples. You'll be working with a lot of different personalities, so talking about how much you love people and enjoy going out to concerts or other public places where you get to meet new people shows that you are outgoing and friendly. Try to keep this answer brief, but give the interviewer reason to want to know more about you. The way you talk about yourself is also important. Be enthusiastic and composed. Show that you are prepared.