The Legend of Korra, Season 3

Korra:
Can't talk. Meditating.

Tenzin:
(amused) You must be at the end of your rope; you hate meditating.

Korra:
(stands up, sadly) I thought that, if I really tried, I might be able to contact my past Avatars- someone who knows something to help me! But I can't. They're gone, and I'm all alone. (glances at Tenzin) Did I ruin everything by leaving the Spirit Portals open?

Tenzin:
You didn't ruin anything. You did what you thought was best for the world, and now things have changed. Change can be good or bad, depending on your point of view.

Korra:
(sighs) I know the people's point of view- it's bad.

Tenzin:
You're not the President, Korra. Your job isn't to fix the daily problems of every person in Republic City. Your responsibility is to bring balance to the entire world- and that means, no matter what you do, some people are not going to be happy about it.

Korra:
(sits down) Great.

Tenzin:
(sits next to her) On the other hand, some people will be very happy. Like me. What you did during Harmonic Convergance may have brought back the Air Nation. And that can only be good, for restoring balance. That is the act of a great Avatar.

Korra:
It's scary. I have all this power, and all these people depending on me... but, I don't know what I'm supposed to be doing half the time! It seems like I should be... wiser.

Tenzin:
True wisdom begins when we accept things as they are. You started a new age, Korra. There's no going back to the past.