The lead single, "I'm Yours", was written in August 2004 and originally released as a free acoustic B-side when "Mr. A-Z" came out. Through Mraz's live performances of the song, it gained in popularity with fans. When he played it at a festival in Sweden in 2007, the fans were ecstatic and singing along, after which Mraz realized the song's popularity and decided to make it the centerpiece of his next album. "I'm Yours" became Mraz's first Top 10 hit on the "Billboard" Hot 100, peaking at #6 on September 20, 2008. It ultimately spent 76 weeks on the Hot 100, longer than any other song in the magazine's 51-year history (a record since broken by Imagine Dragons with "Radioactive" in 2014). It was a major commercial success in the US, receiving a 7x multi-Platinum certification from the RIAA for digital sales of over seven million. The song was also successful internationally, topping the charts in New Zealand, Norway, Portugal and Sweden, and peaking in the top ten on the charts in 11 other countries. By May 2012, it had gained over 125,000,000 hits on YouTube. It was the first song to top the charts in four different radio formats: Mainstream Top 40, Adult Contemporary, Adult Top 40 and Triple A. It also made the Latin Pop and Smooth Jazz charts.