This is another mind body connection exercise. Learn how to activate your core just by simply placing your legs up, draw the lower back to the mat, and tilt your pelvis forward to help activate the pelvis floor muscles and transverse abdominal which translate in activating the core. Also, gultes/pelvic thrust helps activate it too. Do glutes/pelvic thrust exercise first before this core exercise to really activate! This can be confusing at first to grasp but if you simply lift the legs and hold for a while you will feel the contraction and burn( metabolic stress) in the abdomen. Remember to breath inhale and exhale doing any core movements.