I remember as a child feeling joy on a fairly regular basis, and holidays like Christmas or Easter were just pure magic. It's not something that happens very much as an adult anymore. Maybe it's just a side affect of maturity... been there done that or maybe it has something to do with the maturing of the rational mind.
The times that I do feel joy as an adult are usually in response to the unusual or the unexpected. My wife told me that I seemed more excited when the Yankees won their most recent World Series than I was when my children where born. Thinking about it, maybe it's because I had 9 months to prepare for the birth of my children. I wasn't sure the Yankees were going to win until the very last out though.
"Enjoy every sandwich" ~ Warren Zevon