Someone on Reddit posted a link to a short ebook on motivation that is free today, entitled "How can I stop procrastinating?" by Keith Williams. I can't find the link, but here's a summary:
1. Make lists of your goals and separate them into a "must do" A list and a "should also do but less important" B list. Focus on the A list.
2. Break your overwhelming-seeming tasks down into steps he calls "chunks." For example, if you want to clean your house, you would list each room separately. If cleaning a room seems daunting, split that up into areas, e.g., 1) clean the stove, 2) clean the refrigerator, etc. When faced with a large task like cleaning your whole house or writing a book, your mind can run away in fear and decide to procrastinate instead. Creating a list of easily-achievable goals is more appealing, and by checking off things you've done, you create a positive-enforcement loop of pleasure and achievement.
3. Visualize success over failure. Imagine yourself in the future if you fail to live up to your potential and waste your opportunities. See that person, fat, useless, homeless, loveless, friendless, alone, poor (whatever you fear the most). Imagine in detail the scorn your neighbors and ex-friends feel for you because you turned out to be a waste of a person.
Now, remove that image and imagine yourself in a future where you took advantage of your opportunities and became very successful. You are successful, wealthy, fit, with many friends and you have whatever relationship successes you desire, whether that is a perfect wife or whatever you wish for the most. Practice picturing the "Loser You" and quickly erasing and replacing him in your mind with the "Successful You."
4. Reduce stress by meditating every day for 10 to 20 minutes.
5. Exercise every day; it will increase your energy level. Eat healthy and well.
6. Track everything you do so you can see your progress. Having achivements under your belt creates a positive feedback loop, and a lack of achievement demonstrates you're doing something wrong and need to analyze what you're doing.