Sometimes I hear bits and pieces of song lyrics in my head. I find many of them to be particularly relevant, like Dave Matthews asking you "what would you say", or The Who exhorting you to "pick up your guitar and play".
Of course, it’s much easier said than done. There are so many other distractions, as well as necessary duties in life, that there is often little time left for anything unscheduled. As much as I love playing music, I often find that I need to have a goal in mind in order to make time to play.