Your inner child.
Your inner child and your voice have something in common that all writers share. You simply cannot be a writer without it.
When is the last time you have done something childish that you haven't done since you were a child?
Like jumping in a water pit and making your clothes all wet, putting cardboard pieces on your bicycle's wheels to make it sound like a motorbike, or painting your face.
We tend to lose our inner child as we grow up, and as adults it's often completely gone. Evaporated from our mind.