when writers know

I think writers know they have a story when they can't NOT write it. I mean, when they think about it all the time (even while they're working at some other job) and all they want to do is keep writing down the scene that's running through their head. Or multiple scenes. I cannot write down scenes fast enough, yet when I finish writing one, I look at the clock and somehow hours have passed. It's quite joyerrific. I'm excited.