It's easy to get overwhelmed with a really big goal. Ericson Ay Mires at Pick the Brain suggests only taking an occasional peek at your overall goal and focusing on the pieces instead.
Breaking a larger goal into smaller parts isn't exactly a brand new idea, but Ay Mires frames it in a new light using an idea from personal development guru Stephen Guise:
...think of the big picture like a jigsaw puzzle. We use the picture on the cover (i.e. the "big picture") as a point of reference. You shouldn't stare at the cover while putting the pieces together, you'd fumble around and make a mess of things. It's impossible to create something with grace if you don't give 100% focus to what you're doing, so imagine how good your results will be if you don't give that focus to each step you're actually doing (essentially the building blocks of your goal).
So stay focused, but only on the current step. Then your goal will truly start to take form.