“Hatha Yoga is practiced in order to initiate a process in this physical body whereby the pranic currents and mental forces interact with each other in the scheme of life, and existence may be transformed.”  
Swami Satyanada Saraswati, in the foreword to the Hatha Yoga Pradipika.

I  practice and teach Jivamukti  and Hatha Yoga, with the goal of creating an experience of unity between breath and movement, and between body, mind and Self.

Jivamukti Yoga is a path to enlightenment through compassion for all beings. Hatha Yoga is the (physical) branch of Yoga that unites pairs of opposites; its practice is balanced and peaceful. It is a union between exertion, or the dynamic, and letting go, or the static.

“(Hatha Yoga is) the physical branch of Yoga practice. It includes postures (asanas), breathing techniques (pranayama), seals (mudras), locks (bandhas), and cleansing practices (kriyas), Though known for its ability to bring health, flexibility and realaxation, its ultimate objectives are the purification of the nadis (subtle nerve pathways) and uniting of the outgoing and incoming (or upward and downward) flows of prana. 
When the flow of prana is balanced and harmonious, the mind becomes still and tranquil and ready for the subtler practices of concentration, meditation and samadhi. Hatha Yoga helps return the body to its natural state of health and ease.”
From Inside the Yoga Sutras by Reverend Jaganath Carrera

“The ha/tha balance is expressed on the mental level by the internal state of contentment, combined with a desire to improve. Moreover, the contentment never turns into laziness; rather, it enables us to develop. In fact, we come to respect and honor our limitations. With such an attitude, we tend to feel that progress can best be made by avoiding the polarized approaches of either giving up or struggling.
The number one sign of a ha/tha-balanced practice may be that you love it—not just how you feel afterwards, but your enjoyment of what you’re doing as you’re doing it.”
by Swami Asokananda, How To Practice Ha / Tha Yoga (link)