Shatkarmas and Asana purify the body. They build awareness. Awareness sharpens the senses. Regulating the breath increases our ability to produce the agni.
The subtle body is inherently closed for a significant reason. Once it is made open, the subconscious awakens which in turn emerges our karmas. Hatha Yoga is the most powerful in awakening the kundalini. It is also the most dangerous.