Happiness

Why is it that, unlike youngsters, it takes so much for us to be happy and satisfied about things? My two-year-old sister asked one of my brothers to play "Piggy Market" with her yesterday. He began, "This little piggy went to market..." She was thrilled. Such simple little pleasures delight children, make their day. Why is it that as we get older, we need so much more than that to make us content?