I have tried to follow the instructions set out in the book but for some reason when I have gotten into the stretchsitting position I do not feel straight and can feel and see a sway throughout the back and I feel a stretch throughout the mid back rather than in the lower parts. I do not think I am thrusting my chest out because I am curving forward as specified. Also I can not detect any pinch of skin. Anything I could obviously be doing wrong? Thanks.