1. Care: It's as simple, really, as caring about doing a good job. Have some pride in what it is you produce or how it is you help the company overall to succeed. If you genuinely care about doing your job well, that's really all you'll need to motivate yourself and have a great work ethic.
2. OCD: OCD, or Obsessive-Compulsive Disorder, really helps in those tedious projects that just need doing. Spend hours late into the night working at something as boring as updating a database for formatting for the simple reason that everything HAS to be right. Not only with this give you a false motivation to get a project done, but your supervisors will gladly take advantage of this affliction of yours and praise the results!
3. Befriend your Coworkers: If you have a vested interest in the people around you, inherently that comes with a vested interest in how work goes for them. A job well done on your friendly coworkers' part will often help make your job easier, and vice versa. As long as you have a mutual respect for what your coworkers are trying to accomplish and how that fits in with your goal, you will be more willing to go the extra mile on your end. Eventually your coworkers will reciprocate by making something easier for you and it will become a productive cycle.
4. Money: Of course, that's what we're all in this game for, right? Get the jobs that get you the khakis that get you the chicks. I believe it's probably a fact that your work ethic and dedication to the company goes up exponentially as your salary goes up. Don't be afraid to ask for a raise every year if you've seriously been rockin' at work. Be sure to do something that makes the bigwigs take note and want to give you more money and you'll find it's much easier to get out of bed in the morning!
5. Supplies: Make sure you have the supplies you need to do your job. If you're running out of staples, get some. If a certain program would increase your productivity 10%, ask for it and make your case. It's much easier to do the job when you have everything necessary. Once you get into the niche where there's not much else for you to ask for you'll be able to apply all these tools to hone your skills and do a better job. You have to prove to the company that you're worth investing in.
6. Piss off your Friends and Family: This is a surefire way to free up your time for more work at the office. If everyone you know outside of work is mad at you, that removes the temptation (or option?) to go out after work for drinks or spend your weekends poolside with the family. Who needs weekends anyway? Just lost opportunities for more work!
7. Set up Google Reader or Technorati: You can tell yourself that you're just taking time out of your busy day to keep up to date with the latest industry news, but what you're really doing is reading a few industry blogs intertwined with Popsugar or Best Week Ever. If having your own personal interest blogs mixed in with the industry ones make it easier to remember to read blogs, do it. You may not be enriching your working knowledge as much as you'd like to think, but the industry stuff will stick and you'll be able to bust out interesting relevant factoids in meetings and the latest celebrity gossip at the water cooler.
8. Be Better Than Someone: You don't have a lot of control over this, so pick your target wisely. Nothing makes people feel better about themselves than feeling like they're better than someone else. Choose your target- it could be a parent, sibling, friend, or even a lackluster coworker. The smug sense of satisfaction you get from besting this person will be enough to keep you driven every day to never lose your edge.
9. Make a To-Do List: Lists are great because the simple act of making the list gives you something to do in those moments of lost energy when you don't actually want to be working. By making a list you'll find yourself doing something remotely work related, and you may simply motivate yourself by looking at the sheer length of a list of things you have to get accomplished! (The Tasks feature in Microsoft Outlook works great for this.)
10. Have a ridiculously comfortable desk chair: The nicer your chair is, the longer you can stand to sit in it before your desk without having to get up because you're antsy. And of course if you're antsy and walking around the office with a general aimlessness, you're not working.