"One evening, while completing his medical training in Pakistan, Haider Warraich went to the hospital gym to work out. He was in the middle of a set when he heard the sound of a loud click in his back. His body went limp, the weight held above his chest came crashing down, and Haider was rushed into the hospital, now suddenly a patient where just a few hours earlier he had been a doctor. A decade later, Warraich is now an internist in Boston, and...