Dr. Gupta sits down with twins Scott and Mark Kelly after Scott's historic mission of spending a year in space to test the physical and mental toughness needed for a mission to Mars.

CNN's Dr. Sanjay Gupta investigates the science behind a new trend where doctors are prescribing video games instead of drugs - training your brain to be stronger, faster, better.

Dr. Sanjay Gupta explores the world of disease reversal, from Amyotrophic lateral sclerosis (ALS) to strokes to diabetes.