When Breath Becomes Air by Paul Kalanithi

At the age of 36, on the verge of completing a decade's worth of training as a neurosurgeon, Paul Kalanithi was diagnosed with stage IV lung cancer.  Just like that, the future he and his wife had imagined evaporated.  One day he was a doctor making a living treating the dying, and the next he was a patient struggling to live and a new father to a baby girl, confronting his own mortality.