I'll give this a shot. I'll probably win, but that's just because I'm good at most things, convincing being one of them.
I came into this world, I grew up in this world, and I currently exist in this world as a flesh and blood creature. I've experienced pain, love, hunger, dreams, and everything in between. I've sailed above the clouds in planes and dived into the sea at shores both East and West.
But in the end, I cannot convince you without being you. You'll never know if I'm real, if I lie, or even if your own eyes are deceiving you. I am me, and if I have to write more than that to convince you, then it has exceeded the time I wish to expend.
Thanks for the prompt, it was fun. Good luck to me! Photo for bonus points!
Is that a happy rock or some other object extremely pleased to be in the presence of rocks?