If there is one thing I can be certain of in this world it is the fact that I am a thing. My body is a structure that can be broken just like any other thing in this world.
I will make the most of every day while I still have this body and it still works. However I know that I have a short time before my body stops working and I am longer a living being. Life as I know it will end soon within some decades from now.
Even the matter that builds my body is unstable and can break apart. The atoms that I am made of a made mostly of empty space.