Lie facedown on the floor, legs together and straight, arms straight and extended above your head. Keep your head/neck in a neutral position.
Keeping limbs straight (but not locked) and torso stationary, simultaneously lift your arms and legs up toward the ceiling to form a gentle curve with your body. Hold for a slow 30 counts.
Don't hold your breath! Try to keep breathing steady and even. Make it easier: Hold for fewer counts and don't raise legs/arms quite as high. Change it up: Lower to the ground to complete one rep and do a 2-3 sets.