In leading-edge companies like Google and Apple, workers are given much freedom and opportunity to play. They know that's an important component of creating new and better products. I believe that at whatever level of work, cashier at a supermarket, janitor at an airport, aide in a cubicle, the addition of a playful attitude makes the job better and the work more enjoyable. A cashier or janitor who smiles and is friendly gets a better response than a surly one.