Although there are many types of yoga practice, the Vedic literature explains that no matter which practice you choose, success is only achieved when bhakti is present.
What is bhakti-yoga, and how can you add it to your life or your current yoga practice? As bhakti is a pivotal element in any yogic or religious practice, it is known as the topmost yoga. In the Bhagavad-gita, Krishna explains bhakti-yoga to his dear friend Arjuna, and here Srila Prabhupada expands these concepts in this introductory text.
From the back cover:
There are many different types of yoga. Yoga means the system, and Yogi means the person who practices the system. The object of yoga, the ultimate goal, is to understand Krishna. There, Krishna consciousness means to practice the topmost type of yoga. This topmost yoga systems was described by Krishna in the Bhagavad-gita to his most intimate friend Arjuna, and Srila Prabhupada expands this idea here for the benefit of society at large.