The Last Immortal in the World

I woke up to find that I was the last immortal in the world. The Immortal Realm still existed, but the Celestial Court was gone, the immortals were gone, and even the immortal energy had grown incredibly thin. "Immortal, demons are running rampant! Please, save us!" "Immortal, we beg you, please send us some rain!" "Immortal..." Hey, hey, hey! I'm just an immortal who can't be bothered to do anything. How did I become the savior of the world?!