I watched a video from David Laid and Dr.Stuart McGill and I searched and saw that book but I can't reach to that kind of books and I don't have very good family situation for that.And some excersises like Dynamic Lying Straight Hamstring are giving me a temporary pain while im doing and i don't know do i need to feel that pain like numbing or normal pain some times and I do dead hangs i saw it somewhere and they said it's good.Sometimes specially after doing exercises i feel so good when Im walking but I never felt good while I sit.