What I have found over the years is that one can get pretty beat up having fun. After a while, even fun can become not fun. In fact, when I take a vacation, I have to get away from the things that other people do for fun, because I'm just too funned out.
Years ago, a kid asked me what my doctorate was in. I said that Ph.D. stood for Doctor of Phunology -- which would be the work of producing fun. When I designed a coat of arms for myself, I added a motto in Old English (not Latin): Plega is min cræft. "Play is my work."