Actually, the kind that you do against the wall was part of the stuff my dad had to do after he hurt his back. You start doing one against the wall 3 times a day, and the next day, you do two, three times a day, and increase each set by one each day. When you get to 100 (I think), then you start by doing one on the ground, three times a day, and follow the same number routine with those. Depending on how high up or down the wall you do them, they get harder or easier. It helps with learning to keep your back aligned as well, without trying to fight gravity quite so much.