“Wait, I can feel that?” Ami Brasure remembers thinking. For most of us, the experience that dazzled her couldn’t be more ordinary: You’re standing around, maybe in your kitchen or living room, drinking something a little too carelessly, and before you know it, the liquid is dribbling down your chin and trickling down your chest — and you can feel it. It’s a familiar sensation (in this case, perhaps an embarrassing one). But for Brasure, a 50-year-old retail sales manager from the Washington, DC, area, it was life-affirming.  At the time, she was recovering from a double mastectomy...