That's the beauty of backbends. Emotionally we can never be disturbed, for the emotional centre becomes an extrovert. When you do Viparita Dandasana, your head looks backwards, but your conscious mind stretches everywhere. Study by observing how the mind gets regulated. You not only know the freedom in the spine, but also the freedom in the spirit.
B.K.S. IyengarYes, flexibility of body and physical perfection for Yogasana is important. However more important is the state of your mind, Meditative mind. Your flexibility might be excellent but if your mind is not attentive, you are merely doing some physical exercise, not Yoga.
B.K.S. IyengarIs it necessary to practice all these asanas, further and further? Is it necessary to develop scientific researches further and further? To a yogi, the body is a laboratory, a field of experiments and perpetual researches.
B.K.S. Iyengar