Total self-surrender refers to a very advanced stage of spiritual life, so self-effort is indispensable for a spiritual seeker at every stage. In fact, it is very important for him to combine self-effort with the practice of self-surrender.
Coupled with self-effort, the practice of self-surrender can save us from relying on our puny ego. It can guard us from self-deception. Until our mind is properly trained and brought under control, it does not begin to act as our friend. It remains our enemy. It is true that nothing happens except by the will of God. But we think we have a little free will, and we have to channel it in the right direction by right thoughts and right actions. The more we exercise our will in the right direction, the greater is the mastery we gain over our body, mind, and senses, and the more we manifest our hidden, divine strength. We deprive ourselves of this possibility when we do not exert ourselves by right thoughts and actions. Sri Ramakrishna explains with an example: "Just as when a cow is tied to a post with a long tether, it can stand at a distance of one cubit from the post or use the whole length of the rope, so it is with the free will of man. A man ties a cow with the idea 'Let her lie down, stand or move about wherever she wills within that area.' Similarly God has given man some power. And He has also given freedom to use as much of it as he likes and in any way. That is why man feels he is free. But the rope is fastened to the post. And mark this: If anyone prays to Him in all humility, He may remove him to another place and tie him there; or He may lengthen the tether or even remove it completely from his neck....If the practising of sadhana were in the hands of man, all would have undertaken it. But how is it that they can't? There is however, one thing: He does not give one more power if the little that is given is not properly used. This is why individual effort and perseverance are necessary."
The key to proper practice of self-effort coupled with self-surrender lies in the understanding of what in us practices these disciplines. The Katha Upanishad, using the imagery of a chariot, explains the different levels of our being. The body is compared to the chariot, the Self associated with body, mind, and senses to the master of the chariot, the buddhi to the charioteer, the mind (manas) to the reins in the hands of the charioteer, and the five sense organs (the ears, skin, eyes, tongue, and nose) to five horses fastened to the reins. The idea is that the Self is attached to buddhi, mind, and the senses-in that order. If the horses are not broken in, and the charioteer is asleep, the chariot does not take the master to where he wants to go, but wherever the untrained horses take it. On the other hand, continues the Upanishad, if the horses are well trained and the charioteer is wide awake, the chariot reaches the destination. Similarly, teaches the Upanishad, a person who has his mind and senses under control with the help of an awakened buddhi reaches the goal of human life, which is Self-realization.
In worldly people the buddhi is asleep, because it is held captive by mind and senses. Self-effort consists in the seeker identifying himself with the buddhi in order to gain mastery over body, mind, and senses. This requires assertion of the will over the mind and the senses. Self-surrender consists in the awakened buddhi offering itself to God, the Self within. The most important point is that the seeker should not submit himself to mind and senses, but assert his will against them. He surrenders only to the Self within.