My son tells me "I can't draw very good", and I want to tell him that he doesn't have to draw good, he just need to draw. I think kids are inherently creative because they don't yet know the artificial boundaries that we have placed around ourselves. They are more free to experiment, do as they like. Here's famous quote by Pablo Picasso: "It took me four years to paint like Raphael, but a lifetime to paint like a child."
So, when I can, when I remember, I ask my son to draw something... anything. I think (hope) this would pay off in the long run...