“When a patient has a heart attack, a Harvard student instinctively runs not to his bed, but to the library to read about chest pain.” Matt McCarthy is no exception and at the beginning of his medical career he was more of a theorist, knowing a lot but not being able to do much. However, just a year spent in residency changed him radically. At first it seemed that this was impossible - so many failures and mistakes haunted the recent student. But difficult situations, wise mentors and the patients themselves helped Matt McCarthy become a real doctor. A story about this difficult but unforgettable time will help to better understand what a doctor has to go through on the path to professionalism.