The most striking difference between little ones and grownups is that little ones cannot worry, and they cannot worry because they have no past and no future. They live only in the present moment. Just watch children. If they play, they play and don't even hear us call them and don't notice anything that is going on around them. If they eat, they eat; if they sleep, they sleep. There is a beautiful English word which describes how they do whatever they do, they do it 'whole-heartedly', whereas grownups always are half-hearted.