I've found that the most motivated people often think of themselves as being very lazy. Chances are, you already do a lot. The question is probably how to make it easier on yourself to get more done. What are your hurdles? If you're me, you worry about the time and the concentration to do homework. Clearing my schedule is easy, but what if I've had a bad day? What if I'm mad about a class? What if I don't get the homework? Then I have a problem. I try to partition time for things - time for dishes, time for dinner, time for homework - and even just saying to myself, "Okay, it's time to do homework." is helpful, especially if I have five minutes in between to switch gears.
As far as changing your personality, I really don't know. The best I know how is the way I went about trying to lengthen my fuse and chill my temper out (I have a bad one and used to have a flash-fuse). I thought about times I would end up getting angry, and made myself get in the habit of counting to ten every time I felt that heat rise. Maybe every time you catch yourself wanting to do something, give yourself a deadline? Make them small. Instead of "I will clean the garage by Wednesday", instead go for, "I will organize the shelves in the garage by five o'clock" or "I will hose down the car by tomorrow at noon" and go from there.
That's the best I can think of. The main point is to reverse-engineer the problem. You see where you want to be, you see where you are, now the key is to see the path in between.
... did that make sense? >.>