Start in a tabletop position. Place your wrists directly under your shoulders and your knees directly under your hips. Keep your spine completely flat and neutral, with your gaze focused on the floor a few inches ahead of your hands.
Engage your core. Tighten your abdominal muscles as if you are preparing to take a light punch to the stomach. This keeps your lower back from sagging during the movement.
Extend opposite arm and leg. Slowly raise and reach your right arm straight forward in front of you while simultaneously extending your left leg straight back behind you.
Hold and balance. Hold the extended position for 2 to 3 seconds. Focus on keeping your hips and shoulders perfectly square to the floor — avoid twisting or letting your extended hip hike upward.
Return to start. Slowly and with control, bring your right hand and left knee back down to the tabletop position.
Switch sides. Repeat the movement, this time extending your left arm forward and your right leg backward.