8:10 is the stretch I am talkiing about. Initially when I used to do this (IMPROPER FORM For past 3 months)), it would hurt quite a lot + my middle back's skin would fold up. I assumed it was because of this area being unused to the stretching so kept it up. Now I know the proper form, i.e. doing it while keeping the spine upright COMPLETELY. And that doesn't hurt much. Only, now when I do the improper form on the left side, I feel a crick in my back's bones on the left side. This is a sign of thoracic instability, right? And can anyone tell me what this condition is called so that I can research it up?