I also say with backbends, you have to be cautiously bold. Not carelessly bold. You have to descend to the dictation of the spine. You cannot command from the brain to do the poses. As you play with a child, guarding the child from injuries, similarly you have to play in backbends, guarding your spine.
B.K.S. IyengarWe must create a marriage between the awareness of the body and that of the mind. When two parties do not cooperate, there is unhappiness on both sides.
B.K.S. IyengarAs long as you do not feel the serenity in the body, in each and every joint, there is no chance for emancipation. You are in bondage. So while you are sweating and aching, let your heart be light and let it fill your body with gladness. You are not only becoming free, but you are also being free. What is not to be glad about? The pain is temporary. The freedom is permanent.
B.K.S. Iyengar