I hope you didn't just tell them you would do this. You have to show them how you will do this and what past, verifiable, actions demonstrate that you are up to meeting the challenge.
No, I definitely showed this in the interview. I didn't just say, hey I'm a positive guy so hire me. I had examples of how I have been an effective leader throughout the interview. It was an hour and a half interview which I did pretty well in every part except for the one I mentioned but it seemed to be a pretty big part.
I'm not giving much more detail about the situation because it is info I can't share with you peons.