You're right, it's one tough question and being able to put up an appropriate response won't be quite easy. But then again, I guess it's not really about putting up what's appropriate as a response, because just as creating contents, originality matters a lot, and everything else is just a follow up.

I believe ones "THING" goes hand in hand firstly with his/her "INTEREST"

I would love to go all day talking about cryptocurrency, or writing stories, but as those are two pretty different topics, it's gonna be harder maintaining an audience, so I'd say I'm still fair from building a solid audience with my "THING" which I'm also yet to find out.