“A song that makes you happy”
This could mean a lot of things.
“Stronger Than you”, Garnet’s song from the season 1 finale of Steven Universe, makes me me happy just by existing.
(Composed and written by Rebecca Sugar. Sung by Estelle (Garnet).)
Here it is in context:
(uploaded by Afro Presents)
And here’s just the song:
(uploaded by Mswordx23)
But I also want to mention “Chijyou no Senshi” (Warriors of the Earth), the theme from Sakura Wars V.