energy
What is energy?
Energy is everything in The Universe.
How does energy exist?
This documentation asserts The Law of Conservation of Energy observes how energy exists.
You cannot determine how energy exists because the origin of The Universe is unknown.
What are you?
You are an organization of energy in The Universe.
How do you gain or lose energy?
The Law of Conservation of Energy observes energy cannot be created or destroyed; only converted.
So, you gain or lose energy by converting energy in the The Universe.