Listen to I'm A Believer (From "Shrek The Musical" Original Cast Recording) online. I'm A Believer (From "Shrek The Musical" Original Cast Recording) is an English language song and is sung by Shrek Ensemble. I'm A Believer (From "Shrek The Musical" Original Cast Recording), from the album School Run Songs, was released in the year 2021. The duration of the song is 2:39. Download English songs online from JioSaavn.