you have a reality video of "and the day goes on" and you play/sing melody while recording yourself on camera. assuming it had no lyrics at the time, you probably wrote lyrics later on. but is it how you always make your music?
it's always best when the lyrics+melody are born at the exact same time. that's where the truest and strongest results come in. but, with practice, it can be done separately if for some reason you got only 1 first