In an interview with Songfacts, Camp explained that he had actually written the song a few years prior to Smash Mouth's formation. The band he was in at the time, however, thought it wasn't a good fit, so the demo he made lounged around on a cassette for a few years until Smash Mouth's drummer, Kevin Coleman, got ahold of it and wanted to see if it would work. Of course, it did.

After the band signed with Interscope Records with a fully-formed album, company executives pushed to get "Walkin' on the Sun" on the airwaves — and it really took off. 

"It was just about all the things that were going on around me as a young person," Camp explained. "And I'm, like, God, what is going on? I don't understand why this is happening. It's like we might as well be walking around a planet on fire. And that's how it came about."