[There's so many variables to consider. And he can't make a concrete decision without knowing more details about the future. What if a longer life will wind up jeopardizing his future with Katara, his family or Korra's existence? What he has now, even if he won't be alive to experience parts of it... he has to hold onto.]

I can see the value of thinking it, Toph. And I don't think less of you for believing it. I just... don't feel like I'm there. Even with all the bad things I know about, I... I feel comfortable with this future. With... destiny. After all, I had a vision of you before I even met you. Stuff like that? That gives me hope.

[There's a pause.]

And I can feel a little stronger with it all.