Inside every pose there an optimal point of balance, a sweet spot, where all the connective tissues of the body harmonize. It is point of perfect tension between grounding and lifting, flexion and extension, expanding outward and pulling in. In yoga, this “sweet spot”  has the quality of sukha a word that literally means to be in a “good space.” In the Yoga Sutras, Patanjali defines the sweet spot as the moment where relaxation and effort are embodied in equal measure. It is a state of equilibrium where the nerves let go and the breath moves deep in the body.
In the beginning of practice, most people generally have no idea about the sweet spot. They are so accustomed to being under strain that the feeling of equanimity is foreign. It takes time to hit the sweet spot and to know how to stay in it. Sometimes it requires but a small shift—a slight raise of the hip, a subtle retraction of the shoulder, a fractional turn of the spine. When you hit the sweet spot, your mind goes quiet and there is a feeling of serenity and composure inside. This is the direct experience of immersion, a kind of absorption (samadhi) where all the tissues are bathed in fluid.
The fulfillment of  yoga has long been compared to extracting nectar from a fruit. When the practice matures there is a mellowing, a ripening and the nectar flows inside. Finding the sweet spot is to tap this nectar, this most interior juice, so that like an inoculation it moves through you everywhere at once.