The senior years don't have to be filled with aches and pains. At age seventy, Ruth Heidrich has the bone mass density of a woman in her early thirties and a resting heart rate of forty-four. Since being diagnosed with breast cancer at the age of forty-seven, she has won more than nine hundred athletic trophies and medals and has been cancer-free for more than twenty years. In Senior Fitness, the "other" Dr. Ruth shows how to maintain and even increase...