What Motivates You?
This is a fairly common interview question, especially if you are in a sales role.  The wrong answer is, Money.  It may be the truth, but it is the wrong answer.
Try this:

Fortunately, I am highly self-motivated and do not require a great deal of external motivation to be succesful. I have an extremely [...]

This is an oldie but goodie.  A true classic.  a lot of advice you have received is wrong and antiquated.  You must come up with a Real weekness and talk about waht you are doing to fix it.
  Keep this in mind, the way you handle your response to the question might be as important [...]