Lynda Barry's Writing the Unthinkable class emphasized how play and movement (and moving the pen!) are linked with creativity. Emphasis on structure, plot, characterization etc... can stop ideas cold. Not that stories shouldn't have them. Just that one should let the images of the story come first.
On of my favorite kid books is Robert Louis Stevenson's Treasure Island It's exciting, scary and fun.
Where did this book come from?
Do you think Stevenson got the story like this:
Or was he entertaining his stepson with details of a pirate map they painted?
You can probably guess the answer.