Why won't God heal amputees?

Why is it that many of us who have full use of our limbs are still unable to be happy or enjoy life to the fullest? There is a defect in all of us in some form or another, maybe physical or emotional, but we are still required to find a way to be happy and satisfied with ourselves. I think most people who have a deformed child have a happier and fuller family life than those who don't. It is facing adversity and overcoming it that makes a family what it is. Just my thoughts.