How do you celebrate milestone birthdays? 80-year-old John Disterdick of Tennessee didn't celebrate his 80th birthday laying down (unless you count the sit-ups.) He spent the day doing 800 sit-ups, 80 pushups, running, biking, swimming, boxing and rowing as part of a physical challenge to raise money for charity. Watch John in action as he redefines what can be accomplished at 80 years old!