Īśvarapraṇidhāna is the fifth niyama – one of the virtuous observances that constitute the 2nd of the eight limbs of yoga. It can be interpreted as surrendering the ego to the true self (pure consciousness or oneness); a willful acceptance of what is (ultimate reality) rather than living out the stories we tell ourselves. It can also mean dedicating oneself to a teacher or yielding to a higher source.
From a special process of devotion and letting go into the creative source from which we emerged (ishvarapranidhana), the coming of samadhi (oneness with the object of meditation, bliss) is imminent. – Yoga Sutra 1.23
The perpetual agitation and distraction of the mind is replaced by devotion to practice and absorption in the object of surrender. Individual self-interest takes a back seat, offering the fruits of thought, speech, and action to the greater good. Over time we develop a sort of inner compass that more consistently guides us from a place of love, compassion, and interconnection.
It is mistaken to think of this type of surrender as a passive giving up. Rather, it is an active and intentional choice to accept and allow, rather than resist or struggle against, that which is already here. In a sense, when we practice isvarapranidhana we are bowing to an inner knowing that is difficult to describe, but unmistakable when its experienced. By surrendering to what is true, timeless and eternal rather what is wanted or assumed, we open ourselves to possibility, being less constrained by the limitations of bias and conditioning.