The key is to understand why they're asking this question.
When it comes to getting the job offer, having the right skills and experience is NOT enough. They need to see that you'll bring some passion to the role.
They want to know that, when a project has a looming deadline and the pressure builds, there's some amount of "intrinsic motivation" that will drive you to give your best and deliver in the face of difficulty.
So -- if you can answer this question in a way that shows the interviewer(s) that you want this role because of "intrinsic" reasons, you'll be one giant step closer to getting the job offer.
What do I mean by "intrinsic" reasons?
We're talking about your motivation for getting this job beyond getting paid, or being proud to tell other people your job title, or other perks -- satisfaction that comes from doing the day-to-day activities of the role.
You need to get clear on these motivations and communicate them.
Here are some tips to help with that:
First, do your homework and understand the organization and the role at a deep level. Start with their website. Subscribe to their newsletter and social media channels. Read their blog. Look for "behind the scenes" posts.
Second, reflect on the reasons why you're a good fit for the day-to-day activities of this role. What motivates you? From where do you get your energy? What activities would you most enjoy doing?
Third, invest time in crafting an answer that is memorable. After they've interviewed a dozen more people, make sure it's your answer they remember most, for all the right reasons.
That's enough advice to get you started.
If you need more guidance beyond these three tips (i.e. step-by-step walkthroughs, worksheets, etc.) then refer to Interview Success Formula.