Ninety percent of what most yoga teachers do is teach asana practice. While asana discharges stress and so forth, it was never intended to be a standalone practice. The true intent of yoga is personal transformation. What we get out of the privilege of teaching prisoners is the opportunity to focus on our own personal development. You can be of service, and, while helping others transform their lives, you have the deeper opportunity to transform your own. What we teach in prison is how we live our lives.