The fun part about being a creative person... is the imagining. The musing, the pondering, the daydreaming. I can sit and stare into space for hours, perhaps, and build worlds upon worlds in my mind's eye (my high school teachers can vouch for this). I can hear characters speak, I can smell their scent, I can see their facial expressions, feel their hands and arms. It's all wonderful and intoxicating and magical to me. I can imagine 3, 4, 5, chapters at a time. Every scene, each detail, each progression of growth comes alive for me. I see it all.
Until I sit my bum down in a chair, or on the sofa... and actually write... until I make real those words, concrete each vision, each scene, each magical moment... it's all just a daydream. I joke with friends that I've been writing all day in my mind. But the hard truth is this: if the words aren't filling the white space, advancing you in a tangible way toward your goal, than you're not writing.
I do believe it's all connected, and that inspiration can't be forced. I respect the process, I cherish those musing moments where I can just sit and be and let my characters show me the way. But I guess what I'm saying is, you have to WRITE to write. Get the words down, get them out of you, don't leave them swirling around looking for a place to land. They may just get frustrated and leave you. Imagine and dream, but DO THE WORK. Sit, sweat, write it down.
Otherwise, your dream will remain a dream. And what a tragedy that would be, not to tell that story.