This is an absolutely wonderful pose to practice for easing discomfort in the low back, as well as maintaining the healthof the lower spine.

Have a yoga mat or a blanket covering the floor. Come to a position of lying on the back with the knees bent and feet flat on the floor, or on the bed. Now place your right hand on the right knee and your left hand on the left knee and keep the knees toward one another. As you exhale through the nose allow you knees to come toward the chest. As you inhale in through the nose, allow your knees to gently move away from the chest. This pose is done with the legs being relaxed, and just the hands and the breath guiding the movement of the knees in and away from the chest. As you move in this way feel the beneifts of the pose in your lower back. Flow in and out of this pose 6 - 15 times. Then roll over on to your side and rest for several breaths before slowly coming to sit-up and then gradually to standing.
Now go about your day and reap the benefits of this simple, yet profound yoga pose.