Carolyn Senger, a preventive medicine doctor, regularly treats uninsured patients, coaching them how to stay healthy. Now she's teaching them something else: how to sign up for insurance under the Affordable Care Act. "Not only can I help you with your health, but I can also help you get some coverage," Senger tells her patients. In a massive push to get millions signed up for new insurance options over the next several months, health officials are counting on physicians. They're motivated by a long-standing principle: People trust their doctors.