As a psychiatrist, I’ve long wondered why some people get ill in the face of stress and adversity — either mentally or physically — while others rarely succumb. We know, for example, that not everyone gets PTSD after exposure to extreme trauma, while some people get disabling depression with minimal or no stress. Likewise, we know that chronic stress can contribute to physical conditions like heart disease and stroke in some people, while others emerge unscathed. What makes people resilient, and is it something they are born with or can it be acquired later in life?