The great blessing from Jim Henson was, “Don’t think about your discipline, don’t think about your craft, just play at this.” Get thinking about the craft out of the way, and the rest will come to the surface.
Recent scholarly work about play tells us it is a kind of rehearsal process. You play to run through various scenarios about how things might play out, to throw things at the wall and see what sticks. People who get into the habit of play as a way to turn ideas around in their heads tend not only to be more adept at it when they do it, but more willing to engage in that kind of play in the first place: the what-ifs, the counterfactuals.
The most courageous creators do this with their own work, because there's no other way to get it to flourish. Karl Popper believed the theories that survive the most rigorous of tests are the most useful ones, because they are most likely to provide the best predictive value. Great creative work never emerges all at once, as-is; it's the product of a constant toss-and-test. Those who think it comes all at once don't notice all the things that came before it; they don't realize the overnight success spent fifteen years at work beforehand.
Being uninhibited with your work also requires you to not take it very seriously. Not in the sense that you don't care about it, but in the sense that you don't have an inflated opinion of it. You have to be able to see it as raw material, because that's how other people are going to see it too. Maybe not all of them, but enough of them that you owe it to yourself to not kid yourself.
I spent a long weekend traveling and taking it easy in an environment where you're encouraged to let your mind wander freely — in other words, a fandom convention. And fandoms are first and foremost about playing with things. Everybody there is reinventing, reworking, mashing up, dismantling and recombining their favorite things.
I used to have a snobbish resistance to this kind of energy, because I thought it was unfocused, or undisciplined, or what have you. But it's a wellspring that would be foolish to pass up. The more you make a game out of your work, the less it feels like work to begin with.