Flexibility on its own is an imbalance. Strength on its own is an imbalance.
These physical possibilities often reflect our emotional state, weak or strong, moveable or rigid. By balancing the body we bring balance to the mind and emotions. We do this via the breath and movement.
It is fine to understand the mechanics of the breath. But you have to allow your yoga practise to transform your breath without a single thought about it, nor a bunch of words about it. You can't "know" breath. The mind is the opposite of breath. If you are thinking, you are not breathing. If you are breathing, you are not thinking.
Pattabhi Jois said, "Yoga is 99% practice, 1% theory". So enough talking. Your mind is of no help in your practice. We want you to get mindless, wake up your feeling, get full of life, breath, pleasure and happiness and remember how great it feels to be alive and celebrate it for 90 glorious minutes and then every day of your life.