Stack sitting and inner corset?

I have a diagnosis of disc damage at the L5S1 vertebrae.  Earlier 8 Steps told me to skip the chapter on stack sitting, but now in the chapter on the inner corset the first thing I'm told to do is stack sit.  What do I do with this?

ETA - Nevermind.  I more carefully looked at the rest of the chapter.  Forgive me for jumping to conclusions.  Moderators, feel free to delete this thread if you wish.