Even if we assume we could somehow do this, I would recommend you to watch some Star Trek episodes with Q. Living forever can be even more depressing than to live one finite life.
And I'd wary against generalizing from fictional evidence. As much as I love Star Trek, it has one hell of a anti-life-extension, anti-transhumanism bent. Perhaps because it's a story about humans becoming a better people, and for it to be directly relatable, it has to involve humans like us - unmodded, whether by genetics or technology.
I mean you can use your own brain and think about the idea of living forever and the consequences it would have. The more I think about it, the more it becomes a depressing idea at least for me.
I've done that a lot, and I find it an optimistic idea. Sure, we'd need to refactor some things in society to root out the hidden structural dependencies on life expectancy being double-digit years, but other than that? I see mostly upsides.
(And in terms of boredom, because I'm guessing that's what you allude to by invoking Q: you can always decide to end your existence after you get bored with eternal life.)
It's about meaninglessness. Maybe it's just me, but things (including life) that are finite are valuable and special for me. Also in terms of Lord of the Rings I would rather be a human or hobbit instead of an elf. But I respect elves and get your point, it's just not for me.