The Legend of Korra, Season 2

Child-Korra:
How long have you lived here?

Iroh:
Oh, I've been here for many years. I've always enjoyed the company of the Spirits. So when my work was done in the material world, I chose to leave my body behind and come to the Spirit World. It can be a wonderful place, and I've made so many friends. (he notices she is looking upset) Korra, what's wrong?

Child-Korra:
I came here with my friend... but I lost her, and now I'm all alone.

Iroh:
You're not alone, Korra. It's okay.

Child-Korra:
No, it's not okay! Jinora's gone, and I need to find her. She's lost, and we need to go home! I don't like the Spirit World, I don't wanna be here anymore!

[Iroh's spirit friends become deformed and menacing due to Korra's negative energy and dark clouds settle over them]

Iroh:
Korra, please stop! Look at what you're doing to everyone.

Child-Korra:
... I did that?

Iroh:
In the Spirit World, your emotions become your reality, especially for the Avatar, because you are the bridge between the two worlds. You must try to stay positive.

[Korra takes a deep breath and calms herself]

Child-Korra:
... I'm sorry.

[The clouds recede and the spirits become friendly again.]

Iroh:
(beams) There, you see?

Child-Korra:
I can make the sun shine?

Iroh:
Even in the material world, you will find that if you look for the light, that you can often find it. But if you look for the dark, that is all you will ever see.

Child-Korra:
... I'm looking for my friend. I want her here now. [Nothing happens] Why didn't she come out like the sun?

Iroh:
I'm afraid finding her won't be so easy.

Child-Korra:
But what am I supposed to do?

Iroh:
Sometimes the best way to solve your own problems is to help someone else.