I saw the following excerpt in a web site (http://www.yogawiz.com/askquestion/261/asanas-for-reducing-creatinine-in-blood-i-am-suffe.html) which seems useful for doing this asana correctly. "... sit on a yoga mat with spine straight and feet together, legs outstretched. Raise your right leg and place it against outside of the left knee with soles firm on the floor . Stretch your left arm and place fingers on toes if right foot, place the right arm around the back of your waist in such a way that your palm rests on the left hip bone. This is the first stage of this asana, before proceeding to the next level please practice this pose correctly. Throughout the exercise your spine should be straight and head should be in the upwards direction. Do not slouch as this will not only spoil the look of this pose but will also decrease the benefits provided by this pose. So to keep a check on your posture this exercise can be performed in front of a mirror. After taking the position, ta