Lay on your side, hips stacked on top of each other, and shoulders stacked on top of each other - do not lean forward or back, keep that bellybutton pulled in and pelvic floor nice and tight. You can rest the head in your hand as shown, or you can set the head right down. Bend the bottom leg slightly, keeping the top foot parallel to the floor, slowly lift up, do not roll the upper body or hips back. Keep the upper body still, and slowly lower.
Try to resist in both directions.
Modifications - adding in little pulses at the top, little circles at the top.
