The bassist started side project Smoke and Jackal with his friend Nick Brown during his year off from touring with his main group, and they recorded six songs in eight days.
He told Rolling Stone magazine: ''I knew that I would go a little bit stir-crazy just not doing anything and not having any artistic outlets.
''It was super spur-of-the-moment. Nick sings amazing and I sing horribly, so we figured we could just go down [to Nick's basement] and try it one night.''
Nick - who also fronts the band Mona - added: ''We made a rule of 'no pressure. The second: if it's not fun, we're leaving. We'll go to a bar.''
The pair watched films and tried to create their own soundtracks and deliberately tried not to sound like either of their normal bands.
Jared explained: ''All of the songs were kind of a specific sound that our other bands did not go for. We both love our own bands, and we weren't trying to step on any toes. That would have been weird for us.''
Jared also gave an update on Kings of Leon, saying they are in the planning stages of a follow up to 2010's 'Come Around Sundown'.
He added: ''We're just trying to have fun with it and just have a relaxed-type thing.
''We're just meeting with producers and stuff. I think we're going to try and start it this year. We'll see.''