What do a couple of women in their early 80's do after their careers are long over, the grandchildren are grown, and baking cookies or knitting sweaters holds no appeal? They take Pilates and meditation classes on a mountain-top in Utah, of course - and write a book. They write about what it's like to have young, vibrant brains living inside bodies whose knees, hips and other assorted parts are falling apart. They describe how difficult it is to watch your circle of friends and loved ones shrink. And then they describe coping strategies for dealing with all of that. Much of their advice is...