Lie flat on your back with your legs wide. Bend your left leg and extend your left arm up into the air. Place your right arm slightly out to the side, rotated so that the outside of your arm and pinky finger are touching the ground.
Squeeze your core as push off the floor with your right elbow and left foot, reaching your left hand overhead. Your upper body should twist about a 1/4 inch to the right as you come into this crunch.
Keep your abs engaged as you slowly lower back down to the mat.
Repeat for the full 40 seconds.
Once the 40 seconds is up, rest and complete the move on the opposite side.