John Legend's heartfelt ballad "All of Me" has been burning up the charts, so much so that it has become the singer's most popular hit to date, landing him the coveted #1 spot on Billboard's Hot 100 chart a few weeks back. That's quite an achievement for any song, but especially one that strays from those that we usually see at the top of the chart. "All of Me" is a love ballad with minimal instrumentation, much different than those that came before and after, like "Happy" & "Fancy" for instance. The story behind the song is that John wrote the "All of Me" lyrics for his then-fiancée Chrissy Teigen in a writing session with songwriter Toby Gad. The two musicians threw ideas around and came up with the song in under three hours, according to a Toby Gad interview. It's been widely reported that the first time John sang it for Chrissy, she broke down into tears. John would later perform the song at his own wedding to Chrissy, and then later at another set of nuptials, those of Kanye West and Kim Kardashian!