The Start of the End

Studies have shown that those who start something with the end in mind are much more productive then those who don't.
This is true in most areas of life, but most importantly in writing. Many author's write the end of their story long before they ever write the beginning. Or at the very least develop it in their mind before they start.

Think about how hard it would be to build a house without a blue print. It would be nearly impossible. I'm sure there's someone that could do it, every rule has their exceptions, but its just best too accept that you're not the exception.
After all, what point is there in doing something if you don't truly know where you're going? It's the same way with writing a story: have an ending in mind so you have something to strive towards, a guide to follow, a goal in mind.
When you start writing you'll probably find that your story almost never goes the exact way you planned. Most likely the story you start with and the story you end with will almost be two completely different things entirely. That's okay, when plans fall through you make new plans.
So start with the end. It may not make sense to anyone else but to you it's the beginning.