Christy found writing the songs for Duff as "really fun and easy". The Matrix had just completed their work with Avril Lavigne on her debut studio album, "Let Go" (2002) at the time, so they were "in that zone". The Matrix knew that they had a hit on their hands as soon as they began working on "So Yesterday". When Duff heard the song for the first time, she was very unsure about it. Despite her reluctance to do the song, she recorded it and once Hollywood Records heard it, "everybody started sort of freaking out". She later recalled, in August 2013, that it was not one of her favorite songs, but that it "definitely grew on ". Christy recalled the process of working with Duff as being "too easy". She cited Duff as "just a professional" and that the one thing that she remembers the most from working on "Metamorphosis" was that Duff is a "real worker". According to Christy, "Where Did I Go Right?" and "So Yesterday" are among her favorite songs that she has ever written.