Dr. Dan Engle, MD is a practicing psychiatrist, board certified in psychiatry and neurology. Aubrey Marcus is writer, entrepreneur, and adventurer.Dr. Dan Engle, MD is a practicing psychiatrist, board certified in psychiatry and neurology. Aubrey Marcus is writer, entrepreneur, and adventurer.Dr. Dan Engle, MD is a practicing psychiatrist, board certified in psychiatry and neurology. Aubrey Marcus is writer, entrepreneur, and adventurer.