This comes from Princess Trixie Sparkle Episode 7. Applejack has been wounded, but her spirits are still high as she reminds her friends why everything is going to be okay in the end.

Lyrics and Art Editing by: Magpiepony
Performed by: Magpiepony, Itsannachloem, Gloryoftherainwings, Brittney Ackerman, and Mary Medley
Sound Editing by: PegasusPitchVA
Song Origin: "Us" by Regina Spektor