In the movie Garden State Natalie Portman says that what indie song New Slang will change your life?

That's actually a very common misconception! While the movie Garden State features the song "New Slang" by the band The Shins, it's not Natalie Portman's character who says it will change your life.

It's actually the character of Andrew Largeman, played by Zach Braff, who says the song is "the best song ever" and will "change your life".