"When Emily Halnon lost her beloved mother to a rare uterine cancer at just sixty-six years old, she wanted to do something monumental to honor the person her mother had been: adventurous, courageous, inspiring. Emily's mom had taken up running in her late forties; she ran her first marathon at fifty. She learned to swim at sixty so she could do triathlons, and she lived through a grim diagnosis with extraordinary joy and strength, still going for...