"There's one song that I'm particularly proud of because when the Red album came out, there was this one song on the album that I was like, 'I'm the only one who loves this song this much,'" she explained ahead of the performance. "And then when it came out on that album, slowly but surely over the course of that album's life and then beyond, you guys have made that song something that was way more than I thought the life of that song would be."