Smile

"A summoner's confident smile is always a great encouragement to us." This is what a random Spiran said on the S.S. Liki. And it is so true - the summoners are Spira's only hope for peace. Summoners have the most important job in Spira, and so they are some of the most respected people in society. They cannot afford to show sadness or despair, because they are Spira's hope, and if Spira's hope is gone, then where can the people look?

Yuna is a pro at concealing her sorrow. She's always smiling, and she can't always be feeling happy. With such a bleak future ahead of her, Yuna has little reason to be happy. Even so, she rarely breaks down, and even then, in front of only the few she trusts the most. As she says, summoners are Spira's ray of light. "A lot of people in Spira depend on us." As she tells Tidus, "I learned to practice smiling when I'm sad, you know? I know it's hard." Tidus can't always tell when Yuna is smiling for the sake of others' comfort and reassurance.

The summoner's pilgrimage is not a joyous parade. The summoner and his or her guardians know that they're walking down the path to their own deaths. No one wants to reach the end, and yet they know that they must if they want to work for the greater good. This is why Yuna wants her "journey to be full of laughter." Even at the most mentally exhausting and difficult moments, Yuna hopes that the party can try to be cheerful. Overlooking Luca, she and Tidus force themselves to laugh. This is one of the most ridiculous scenes in the entire game, but it really communicates that Yuna is trying her best to keep everyone's spirits up even though her own heart is breaking.

She always tries to put up a brave face in front of others. As Kimahri says, "If we worry, she tries harder. Do not frown." Yuna has to show a happy face. As Tidus tells her about Zanarkand and how they can go back after she defeats Sin (since he doesn't know that she will die), Yuna just smiles and nods. She is excited by the prospect of seeing it, she is happy for a moment's peace in front of the ocean, but she knows that it can never happen.

Over the course of her pilgrimage, the party shares a few lighthearted moments. They laugh about small, trivial things. Tidus, as the outsider, later realizes that he was the only one who was actually laughing. "Laughing must have been the only thing keeping them going.".

The same carries over in FFX-2. She's saved the world, and yet, she cannot be truly happy, because she lost so many friends in the battles with Sin. She's much more vivacious and cheerful without the weight of Sin. She's usually smiling to others around her. But when she's alone, melancholy steals across her heart, and she can't help but feel sad.