by lying on the floor on your back, with your arms above your head and legs
straight out. Then pull your arms down by your side and lift your legs an inch
or two above the ground. Your back should be the only part of your body touching
the floor, and your lower back should be rounded and in contact with the floor.
Do not let your lower back arch and come up off the floor; this would place
harmful stress on your back.
Hold this position for a set amount of time (between
15 and 30 seconds). Rest and repeat for the same number of seconds as before.