I suffer from pain in my low back as well as pain in the upper back (shoulder blade), so I purchased the book and began Stretchsitting when working at the computer. However, I find that my neck becomes tired from this position, even after following the neck straightening procedure described in the book. This is because my back is angled backwards while stretchsitting. If my back was perfectly straight, the force of gravity on my neck points straight down through my torso, so my neck muscles aren't stressed. But because my back is angled, the force is angled as well and so my neck muscles are having to work hard to prevent my neck from falling backwards. Is this normal? Will I get used to it, or should I change my posture/do some neck exercises?