Perhaps try setting a time limit, say... "I will work on my math homework/essay/whatever for 10 minutes. And then I will reward myself." And then reward yourself with something fun... 10 minutes on PC, a really yummy snack, or an episode of your favorite show. After your reward, do 15 minutes of work. You might find once you get started, you'll keep going for longer than you told yourself to work for. Also, try to cut down the distractions. Maybe try to find someplace where you don't get internet, hide and turn off your cell phone, go into another room away from TV and people. Maybe using a timer for both the fun and the reward will help you keep on track. I'd also start this tactic earlier rather than later. A, you can see it could take a really long time! And B, procrastination can lead to anxiety.

Hope this helps!
Good luck! I totally understand how you feel!