Are Limits the Stuff of Meaning?

I was interested in your comment that if we were immortal, we would have to simulate death. This seems to be the crux of your argument that we absolutely need limits. Otherwise, we would just twiddle our thumbs for a billion years. There's something intuitively right about this idea that if you don't have anything to battle against, you are not going to flourish in some sense. I mean, one of the things I look at is what does it even mean to speak of being immortal?