Stir Crazy?

The other day after school I gave each of the kids a little bag with snacks in it and told them they had to eat in the kitchen. I returned when I heard uncontrollable giggling and expected to see them at the kitchen table, but instead found them all sitting on the kitchen floor - spinning on their bottoms like tops. It was truly funny and exhibits the phenomenon of childhood energy. Where does it come from? More importantly . . . where did mine go?