Your vision can be a raging fire that might change the world. But you can't have a fire without a spark that takes hold.
So, I learned not to let go of that vision, but to take my head out of the clouds and bring myself down to earth. It's easy to have a big, romantic notion; it's much harder to put the actual nuts and bolts together to get a real venture off the ground. To do that effectively, you have to find: the real people you want to serve, get to know them personally and gain really unique insights about their needs, and then build the smallest possible thing that will meet those needs.