This pose turns up the heat, Harkness said, so keep breathing smoothly and deeply, and rest when you need to.
Get into a strong plank and firm your arms, belly, and legs, so everything is engaged.
Begin to hover your left foot a few inches off the ground, so the weight is in your hands and right foot.
Take a deep breath. On your exhale, draw your left knee to your chest and push the ground away, rounding your upper back.
On your inhale, straighten the left leg behind you again to hover your foot. Repeat this with your breath five times. Then, switch and do the other side.
Remember, you can rest between sides and modify this move by keeping one knee on the ground to make it a bit easier.