It's also more of a Yuuya song but can still sometimes fit with Julien, too. Yuuya is very very good at laughing and appearing casual when he's in great pain. Julien... Well, it's Rilo Kiley's A Better Son/Daughter. For the lyrics, yes, but also that agonized way they are sung.

But you'll fight and you'll make it through
You'll fake it if you have to and you'll show up for work with a smile
You'll be better and you'll be smarter and more grown up
And a better daughter or son and a real good friend

And you'll be awake, you'll be alert, you'll be positive though it hurts
And you'll laugh and embrace all your friends
You'll be a real good listener, you'll be honest, you'll be brave
You'll be handsome and you'll be beautiful
You'll be happy