I came across the above quote in an interview with Ian Rankin, the author of the Rebus crime fiction books.
I think this is a such an important point about creativity. If we really want to let our imaginations flourish, don’t we need to stop being too serious, and setting it artificial limits. Have you seen how rich a life children create with their imaginations? It’s a constant inspiration!
So, with all the serious advice around about happiness, health, flourishing, etc, here’s an additional piece with quite a different flavour – play with your imaginary friends!
Heroes Not Zombies 
artist are the same way