John K. Addis
I'm actually not sure I've ever had "writer's block" in the traditional sense. I tend to have a great many ideas bubbling up all at once, so knowing which ones NOT to develop is the bigger challenge.
It helps to have to create stories nearly every day as well. For nearly five years, I've told my daughter a nightly bedtime story off the top of my head -- and for the last three years, it's been an ongoing 500+ part saga called "Bob and the Birds." With over three dozen recurring characters, talking animals, and magical elements, it's pretty easy to create new tales every night without repeating myself. Usually I'll weave in some sort of lesson that relates to things she experienced during the day, but sometimes it's just an excuse to be silly and make her laugh.