Here is a quick and dirty list of tips I compiled from this discussion on Slashdot

A healthy body leads to a healthy and less distracted mind
-Get exercise.
-Sleep regularly and get enough. Try to get sunlight early.
-Eat healthy. Try to avoid overuse of caffeine, especially soon before sleeping.

A healthy mind
-Realize that not getting things done leads to guild and worry, which only makes it harder to get things done.
-Imagine yourself as a successful person who gets things done through meditation and self hypnosis.
-Feel good about each step that you get done. Perhaps treat yourself with a small snack or other reward for big milestones.
-When you get work done early, allow yourself to relax and enjoy the moment. Do something special like see a movie or do something fun.

The biggest problem is often just getting started because the task seems too big.
Break large tasks up into smaller tasks.
-Break books into chapters or numbers of pages
-Break assignments up into stages and pieces, such as an outline, then each part of the outline.
-The thought of cleaning the entire house may be daunting, but certainly the thought of loading the dishwasher isn't so bad (user #6546213)

Minimize distraction
-Turn off TV
-Keep a notepad so anything you might start to worry about, or any ideas you don't want to forget, you can write down. Then you know that you will remember to take care of it later, and can keep working on the current task.
-Keep a clean desk, a cluttered environment creates a cluttered mindset. Clean the area during study/work breaks.

Other advice.

From user #6545723

My wife has worked with ADHD kids and tells me this is the best thing she's seen to focus and motivate them to produce (other than intrinsic motivation, which is of course the best motivator, but this technique does lead to intrinsic motivation).

Think about what you should be able to accomplish in 15 minutes. Set an egg-timer for 15 minutes, and do that task you visualized. You can eventually work up to larger increments. You'll probably find yourself beating the timer in some cases.

I know it sounds simplistic, but knowing that pressure seems to be a large motivator for you, the motivation of knowing that bell is going to go off sounds like it might do the trick. This stuff works on adults as well as children. In my wife's experience, it's never failed her (with her students).

From user #6545023

Make yourself a home office in a well-heated room, and keep only work-related things in it. When you go to study, take in all the food, caffeine, and books that you'll need for a stint of about five hours. Set an alarm clock to go off in five hours. Now, close the door, and take off your pants. Yes, you heard me, take off your pants. If necessary, take off your shirt as well. Put them in a plastic bag, and tie the bag shut. Put the bag away (the further away the better.). This way, you can't leave the room suddenly without raising eyebrows: If, say, you have a sudden impulse to jump up and watch TV, or phone a friend, it'll take you a good five minutes to dress, which should be plenty to reconsider and sit back down.

After a couple of months of this, you get in the habit of staying in the room until the alarm sounds, you don't have to take off your pants anymore.