According to Garbha Upanishad

Having obtained this intelligence, (When the body comprised of the five natural forces acquires intelligence by the infusion of the jivan जीवन (or the soul), it also acquires the five intellectual organs and the brain, which enables the jivan जीवन to distinguish between different forms of objects and tastes.) the jivan जीवन immediately starts contemplating on the eternal syllable “OM” ओम. Once he digests the essence of the same, he understands the fact that the eight basic forces (five sense organs, the mind, intellect and ego) and their sixteen modifications belong to self, the soul or the jivan जीवन residing in the body.

Whatever is consumed or drunk by the mother passes through the nerves dovetailed with the child’s to the jivan जीवन, which is satisfied with such feed. It is during the ninth month that all the sense organs and intellect organs attain completeness. And during this time, the jivan जीवन is reminded of its previous birth and it realizes all the good and bad deeds it committed during such previous birth.

Thus thinks the jivan जीवन: “By me thousands of birth points (vagina) have been seen; various foods have been tasted; and innumerable time’s mother’s milk has been drunk (to convey that the jivan जीवन had various mothers during its earlier births). I have born and died again and again. All my near and dear (of earlier births) for whom I performed various actions (in earlier births), whether good or bad, have enjoyed the benefits of my actions and have left me all alone. I am left behind all alone.

When I get out of this womb, I will take refuge in Sankhya-Yoga संख्या योग, which destroys misery and yields liberation; when I get out of this womb, I will take refuse in Maheswara महेश्वरा, who destroys misery and grants liberation.

Once I come out of this birth source (vagina), I am going to surrender myself to the destroyer of all sins and the Salvation provider –called as Naaraayana नारायण (or the Supreme Being called by various names). Who destroys misery and grant liberation. When I get out of this womb, I will meditate on the eternal Brahman ब्रह्मा ।

I am going to practice the Gyaana Yoga ज्ञान योग (the pursuit of knowledge) strictly to destroy all my sins and to release myself from the bondings of all actions in this materialistic world. Once I come out of this birth source, I am going to contemplate on this Supreme Divine Brahman ब्रह्म – These are the thoughts of the jivan जीवन during the time it remains in the womb.

However, when he reaches the birth source (vagina) and comes out of it with great difficulty on to the earth, he is inflicted with the illusory force (Maya माया) created by Vishnu विष्णु and immediately forgets all the previous births and the deeds performed therein। His memory is cleansed of all the history the very moment he first inhales the air after coming to the earth.

Unless man does all he can, to attain Godhead, the main pain that he is going to encounter after death, is that he did not attain the real objective of his life, which happens to be to realize his true Spiritual Potential.