I'd recommend looking on YouTube,
"Life After Layoff" has some good interview advice. There's many more, but that's the one I remember right now.
Generally, the response should be related to you're "professional life", not your private one. They don't care that you have 6 brothers and sisters and like to hike - your looking for a job, not a date. If your job happened to be for a national park baby sitting children, then your personal life just became much more relevant.
This question can be used to naturally lead into the "where do you see your self in 5 years" question, by talking about some of your career goals (if relevenat). Let's say your goal is to be a park ranger, and the job your appling is to go around the park cleaning up - that's a reasonable jump. If your planning to leave the job after a bit, don't tell them anything to make it obvious.
If you can bring relevant past expirances of things you did (not just job title) into the conversation that's good. Maybe you used to work at the local park keeping it clean from the local teens, advocated for trashbins to be installed and you want to continue taking care of nature on a larger scale.
Obviously those examples are completely made up, but including expirances to your responces can make a huge difference.