So for a long time now, I've been having trouble getting back into my old writing habits. The reason is just simply because real life had gotten in the way a lot as it has a bad habit of doing. Between work, family time, college, and other things, I just didn't have the time to work on my books anymore, and I could never get back into writing for a long time. But then I got this idea. I asked my grandmother if she could give me a penny for every page I wrote, and told her to give me a deadline for X amount of pages by the end of the week. If the amount of pages she wanted was ten, then I'd write ten pages and get ten pennies, and if I wrote more than the assigned amount, she'd bring me a pop or something from town when she went out.
Thus far this method has proven fairly useful. It kind of tricks your brain into thinking writing this book/fanfiction is a job of some kind. And it's not like you're ripping anybody off. I mean...these are pennies we're talking about here. If you write a hundred pages, then someone owes you a dollar at the most.
If you're having trouble with writing a book or something, why not give this method a try? Ask a friend, your spouse, brother, sister, mom, dad or whoever and see if it helps.