Forget it.
Writer's block: take THIS!
All you need to think about when writing a picture book:
"Would a child give a DAMN about this book?" ~Mem Fox, author
When laboring over the start of your novel, think:
"If you were my friend telling these first ten pages to me in the grocery store, how would you start? How would you tell me?" ~Jordan Brown, Walden Pond Press
When agonizing why your R&R didn't make the cut, just realize - it wasn't the best fit anyway, because an agent and editor will only take it on:
"If I have a clear vision on how to fix it, a clear vision for how to make it sing." ~Alison Weiss, SkyPony Press
And remember:
"Envy is a good emotion if it drives you to be better." ~Jordan Brown.