Unfortunately, there's only one way: Write, write, write. That means stop distracting yourself with websites on the internet and just write the story.
The good news is that after a while of forcing yourself to practice (at least a month) your brain actually starts to change. It won't seem like such a big deal to get down and tackle the work, and you'll be able to work with a great deal of focus.
The best thing to do is set a routine of at least an hour or two everyday. No matter what, stick to this routine every single day. Don't let yourself go to sleep without writing for a full hour!