How to: Feet and knees should be parallel to one another. Place a block on the narrowest setting between the inner thighs, as close to the pubis as is comfortable. Drive the heels of the feet into the mat to tuck the tailbone toward your feet, scooping the low belly in and sealing your low back on the mat. Squeeze block between your thighs as you lift the hips. Roll your inner thighs down and lengthen the tailbone toward the backs of the knees. Reach your knees forward, contracting your thighs and softening your gluteals a little. Draw your heels back simultaneously, engaging your hamstrings. Try lifting your heels to create more space in the low back.