The fears of aging have been one long cascading domino effect through the years: twenty year-olds dread thirty; forty year-olds fear fifty; sixty fears seventy, and so it goes. And there is something to worry about, though it isn't what you'd expect: research shows that having a bad attitude toward aging when we're young is associated with poorer health when we're older. These worries tend to peak in midlife; but in Lighter as We Go, Mindy...