The Bhagavata Purana elucidates the play of Krishna in many different settings and situations. The song-stories are teaching stories about the practice of Bhakti Yoga in order to attain union with the divine.
Yoga has always focused on "perfect alignment," in which the spine returns to its natural positioning over time, as yoga is practiced. Because of yoga's focus, relaxation must actually be achieved at the same time as the asanas are being performed, which can actually be a challenge to those who have only done traditional exercise. Nonetheless, this "relaxation and focus" is key to yoga's benefits, and teach students concentration; as poses continue, focus can intensify to a meditative state.