By the time (in your life) you're old enough to be interviewing at Delta, you should have a fairly good sense of who you are, and you should be fairly comfortable with yourself. That implies some understanding of your strengths and weaknesses. I think that, if you're truthful enough, and able to reflect on your weaknesses, or your hardships, and create something positive out of them, you're fine.

Then again, we don't always think about our childhood, our relationships, or a lot of the pieces of the puzzle that make up who we are. So I don't think it's a bad idea to sit down with a really good friend, and have a little practice. I'm not talking about gaming the system to look for right answers: I'm talking about making sure you think about yourself enough that you can explain who you are. I don't think it's a great idea to sound rehearsed, but I don't think it's a great idea to start thinking about some traumatic event event in your past, for the first time, in front of the shrink.