Asking “What do you find fulfilling? Can take your conversation to a whole new depth. Do not use this question too often with the same person. That can make it sound like you are working off a script. And that is something people do NOT like.
Before you ask this question be sure you spend a reasonable amount of time hearing and reacting to the suggested conversation starter question discussed here. Be sure to read that post!
One great place to use this question is when there is a long pause in the conservation. Like when you out in a boat together fishing. Or maybe just the two of you around a campfire.
I would not use that question in a group since you are likely to get a canned response that does not deepen anything. Except maybe the boredom everyone is experiencing.
You will know you have hit “pay dirt” when the answer to “What do you find fulfilling?” suggests an unmet emotional need.