You must fill every inch of your body with the asana from your chest and arms and legs to the tips of your fingers and toes so that the asana radiates from the core of your body and fills the entire diameter and circumference of your limbs. You must feel your intelligence, your awareness, and your consciousness in every inch of your body.
B.K.S. IyengarI 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. Iyengar