WEEK 3
9. One-Arm Bridge: Advanced Exercise That Builds Your Core Muscles

Hold for one minute on each side of the body.
Lie on your side with the hand that is under your body on the floor slightly ahead of your shoulder.
Stack your feet so the outside of one foot is on the floor and the other foot is stacked on top of it. (You can rest your feet against a wall if you need to.)
Prop yourself up onto one hand, so your arm is fully extended. When your arm is extended, your hand will be in front of your shoulder.
Raise your other arm to the ceiling and look up. Keep your hip and pelvis in line; as you get tired, try not to let them drop toward the floor.
Hold for one minute, then switch sides and repeat.