So the question is, how can you be the body? If you were the body eight years ago, then you would not exists today, because the body you had eight years ago does not exist today. Do you understand this? It's a very simple thing, and yet it's very hard to grasp because it's such a gradual change of our body. It's hard to hold on to. If you were your body eight years ago, you would not exist today because the body you had eight years ago doesn't exist today. So the only conclusion we can come to from this is that a person is not the body.

You are not your body, nor are you any part of your body, because there is no part of your brain or any other part of your body that was present eight years ago that's present today. Yet you are the constant feature. You existed 15 years ago. You remember it. You were there. You existed 20 years ago. You remember it. You were there. And now you exist today. You know that you are the same person. You've got a different body. You were there! That's how you can remember. And now you're here. Try to understand this. You are the constant principle, the self. The self is the constant. It remains, it exists, while the body's changing.

Jagad Guru Chris Butler, founder of the Science of Identity Foundation

For the soul there is never birth nor death. Nor, having once been, does he ever cease to be. He is unborn, eternal, ever-existing, undying and primeval. He is not slain when the body is slain.
BHAGAVAD GITA 2.20