Sometimes the idea of "work" brings people to shudder. I like the statement that Paula made that the things we do for play were what primitive cultures did for work. In a way, I believe that work and play can be very fuzzy. With "work" there are expectations that one is working towards and "play" doesn`t have an outcome in mind.
For example, I played basketball in high school and a couple years in college. There were times that basketball was a lot of work. Running ladders, doing repeated shots, practice, etc. My coaches had high expectations and expected us to give 110% or go home. The results mattered and at the end of the season, it was all about the wins, losses, and playoffs. But there were a lot of times that basketball was just fun--didn`t matter what the stats or score were, just about having fun. Both were important though.