Get into a full plank. Bring right elbow to floor under shoulder, then left elbow to floor (so you're now in a forearm plank). Then straighten right arm followed by left to return to full plank. Repeat for 30 seconds, then switch the lead arm.
Begin in full plank, hands on floor under shoulders. Bring feet together to touch, then jump feet out to sides, as if doing a jumping jack with your lower body. Jump feet back together, keeping upper body as still as possible. Continue for one minute.
Being in a forearm plank. Walk feet as close to elbows as possible, lifting hips toward ceiling. This is your start. Lower chest and head in front of hands, then lift hips back to start. Repeat for one minute.
Sit with legs extended in front of you, palms on floor under shoulders, fingers facing body. Pressing into palms and feet, lift hips, forming a straight line from shoulders to feet. Hold for one minute.