Happy or miserable would be subjective based on how the person takes it. But I can tell you the "prematurely age" part is simply because of the amount of work it takes to raise a child. This is universal, for all children. I don't think anyone who doesn't have children can correctly estimate the amount of work and effort a child takes to raise. That amount of work takes a toll on your body and the aging is the result you can observe of that parent.