If I need motivation to finish something, I just think that it can't go on forever. The sooner I do it, the sooner it is over.
If I am bored: I would love to be bored. Right now my favorite thing to do would be to sit around the house ALL day, watching TV.
But really, I try to start things and set goals and a definite time line I need to reach the goals by. Then I reward myself.
I also do not give myself into temptation if I know the it would be too much. If I need to work on a report or something, I don't go near a personal computer. Instead I go to the library, where I am not tempted to do something devious.