I guess for me the physical asana has always been a tool to go inward. I encourage students if they are stuck at a posture not to look outwards (i.e. towards Facebook or youtube videos) for an answer, but to be present with that discomfort and see what it brings up. Even the frustration, anger and sadness – or whatever emotions may arise - are important. So often these days, people try to avoid sitting with that by putting too much emphasis on mastery of the physical. But our struggles in practice are meant to help us develop concentration and internal focus.