In this work, people are often hesitant about play. "What's the point?" they ask. "I don't need to have fun, there's work to do." Yes, there's work to do. That is why play is so vital.
Here's the thing: the laughing and having fun is not the point, it's a joyful byproduct of a "serious" practice. If you want laughter to be the point, do laughter yoga (beneficial to many, and my idea of hell!).
Think of play as a work-out for your creativity muscles, for your brain and for your joy receptors.
A playful, state is a change state, a fluid state, an open state. A playful state, where laughter is genuine and you go after your aim (whether that be to catch a ball or count to ten in a group with your eyes closed) makes learning, retraining and the formation of new neural pathways quicker, slicker and easier.
So if you want work to work better, play!