To put it into context, a sudden moment where you notice the world around you and the things you have experienced... and how amazing life is.
You're having an epiphany:
A moment of sudden and great revelation or realization.
Here's a term you might like, "anagnorisis". It was used in Ancient Greek Tragedy to define a moment where the hero made some sort of important discovery.
To put it simply, the word means,
the critical moment of recognition or discovery
so it would be a great word to use to describe a moment when you realize that you're alive
Self-consciousness/awareness: awareness that one exists as an individual being.
Qualia: individual instances of subjective, conscious experience.
Memento Mori: "remember (that you have) to die" is the medieval Latin theory and practice of reflection on mortality.
Solipsism: the theory that only the self exists.
- Knowledge or awareness.
- Attend to; take account of.
These two definitions combined work for me.
Word for the realisation that you are alive? Awakening.
- To become aware of something (intransitive verb); "She awakened to the fact that everyone was staring at her expectantly."
- To cause (someone) to become aware; alert or enlighten (transitive verb); "The slam of the door awakened him to the realization that she was never coming back, and that he now faced an uncertain future of coping with the holes in his life that she left behind."