At what age do you forget?

Childhood is so carefree, so fanciful, so fun. And, I want to know at what age do we abandon the simple joys of life: the thrill of pushing the elevator button, the excitement of switching beds with your sibling for the night, the delight of receiving the paper towel roll when all the paper towels are gone, the hilarity of bopping your baby brother on the head with a diaper over and over as he belly laughs, etc.? And more importantly, why? Why the constant effort on behalf of adults (myself, first among these) to stifle what is so very clearly "the good life?" Kids get it. They know what life is all about. We would all do well to immitate them, embrace those simple joys and remember rather than forget.