Some Yoga teacher training courses focus on asana as a physical exercise. This is a shame because asana is much more than an exercise for the body. Asana has therapeutic value and it is a means toward Samadhi as described by Patanjali.
Which asanas or postures should you select? Some Hatha Yoga teacher certification courses have specific sequences, but many do not. How long should you hold each posture? What is the benefit of holding an asana for minutes at a time? Should you start or finish class with meditation? How should you incorporate pranayama within your class?