I think you become enlightened when you realize that you become what you think about.
And if you can control what you think about, you can control what you become.
I think you are on the right track, but I will add this: what you are isn't a product of thinking, and you can't add anything to your true essence. In other words, you are already fully complete and have no need to "become" anything more because it's in knowing yourself that you feel and realize that you are complete. It's the perceived "need" to become something that keeps you trapped in duality. That's what the enlightened have realized directly.