What's something that started as one line on paper?

Big things don't start big. They start with one sentence you half-believe when you write it.

Mine was: "Build a tracking app for this method."

32 days later, it existed.

I'm not saying writing things down is magic. I'm saying it's easy to forget how many things started exactly that way.

What's something you wrote down that eventually became real? Doesn't have to be dramatic. Just true.