My number one challenge is doing yoga in a crowd of people and a room of mirrors. It’s all distraction. To the extent that I find some individual distracting, that throws me off. To the extent that the distracting individual is me and my image in the mirror, even worse. The mirror in my mind’s eye is worse yet.
The worst thing would be to do yoga in isolation. Distraction is the background noise of our existence. You must train in a thoroughly distractive, self-consciousness-conducive environment in order to cultivate the purest poise.