Nora Watts wakes up at 4:50 a.m. on days she’s working.The 65-year-old gets up, dresses and goes to the gym because she wants to ensure she’s in-shape enough to perform her duties as a nurse at Newton-Wellesley Hospital.“I’m not a spring chicken anymore,” Watt said. “I want to make sure I stay strong and healthy.”The job has become more difficult and more dangerous in recent years, Watts said, in part because nurses [...]