First of all, I clickbaited you, since I don't know the answer to that. But I do have an idea about how to prolong your life for eons (or until the end of humanity).
To understand my reasoning, you need to have some basic understanding of the world around you. I've laid out the important concepts for this topic as postulates. You are free to question them, however, and do your own research (and should), but don't waste your time asking about them ITT as I have no intention to waste my time.
1. Souls do exist. Souls can have different volume. It is possible to increase the volume of your soul.
2. Spirits do exist. While human exists on both material and immaterial plane, having both body and soul, spirit only has a soul and thus only exists on immaterial plane and unseen to the untrained eye.
3. Spirits can't increase the volume of their souls by themselves.
4. Universe has a constant amount of mass and energy.
5. Upon death the soul of a human returns to the Great River (basically just a mass of energy also called God by theurgists) where it is torn down to become basis for other souls.
6. Spirits, on the other hand, constantly lose their soul energy to the Great River, until there is nothing left of them.
7. Human can become a spirit.
