What outside activities complement your work interests?
The interviewer is interested to see if the candidate's personality is reflected in both work and outside activities. Your answer to this question will shed light on your personality and thus possibly on your compatibility with the job.
"I've always enjoyed tennis. In many ways it's a game of strategy and pacing. When something isn't working in the first set, you have to change your strategy for the second set. You also have to pace your energy in case you go to a third set, and constantly watch and read your opponent's reactions. I'm a gutsy tennis player-I go for the big points sometimes-but I'm careful with timing. That's the way I work, too."