All the old but happy people I know have children (and grand children). The more, the happier. All the grumpy old people I know have no children, or just one.

All the old but happy people I know have children (and grand children). The more, the happier. All the grumpy old people I know have no children, or just one. On a day to day bases, it might feel like taking care of children is plenty stressful, but in the long run it's the ultimate form of joy/happiness.