"Baby Barbara"

Beginners: 2 rounds through of: 10 pull ups( chin over the bar by kipping, jumping, or dead hang), 15 push ups(regular or on knees), 20 sit ups, 25 air squats(just using your body weight)

Intermediate: 3 rounds through of: 10 pull ups, 15 push ups, 20 sit ups, 25 air squats

Advanced: 5 rounds through of: 10 pull ups, 15 push ups, 20 sit ups, 25 air squats

Once you finish each round you get 2 minutes to rest before starting the next round. So after the last squat you have 2 minutes before starting the pull ups. This should challenge you metabolically more than it should cahllenge your muscular endurance. Post times to comments.