The Way To Improve My Self-control!

I just found I'm really poor in self-control. Ever night when I go to sleep, I will think what should I do tomorrow, where I should go tomorrow. But I will just go to pick the easiest things or my favorite things to do first every morning. For example, I'm a junior now, and I need to take SAT next year. I always think I need to practice a lot, but in fact, I didn't do the practice anymore. I will usually spend most of my days in my interests or easy things. I think I am totally lose myself in it.
Every time when I go to school, I will think if there will be a holiday for me, I can do much more useful things than I'm in school. However, the true is my plan are good, but I will just do very little things in the plan. Instinctively, I am kind afraid to do the things that I don't like. But there are a lot things which I hate must be done. When I recognized my problem, I searched many books about how to solve it because I know it's a bad habit that many people have.
Although I know something are very useful and important to me, I will not it. In other words, I can't control myself to do the right things. I just follow my instinct to pick my favorite and easy things to do.
Finally, I found the problem with self-control are from attitude and laziness. If I want to get more things done and learn more, I must change my attitude. I should not regard many things as duty. I need to enjoy them. For example, there are two sculptors. If you ask the first one: what are you doing? He will say this is one part of my job. I must finish it first before I come back home. The first sculptor always says how hard his job is. If you ask the same question to the second sculptor, He will say he is doing some great art. This guy is always proud of himself and his work. He enjoys it all the time.
I agree it's easy to know and say this idea, but it's kind hard to change the habit. However I found solution for me, I always give myself a goal first, and then try to figure out what I need to do to achieve the goal(I think many people think the same way). But now I think I was totally wrong. I didn't mean set a goal for me is wrong. To set a goal for myself is a really good start, the goal means the things I like, want, and I have enough desire and interests in it. However, if I tell myself if I want to achieve this goal I need to(or must to) do something, I will be totally wrong because I separate my interests into something I dislike. For example, if I want to become a great business man, I'd better tell myself to do a great job in high school and get into a great business university like Columbia is one part of my goal(become a great business man.) Then, I think I will enjoy learning SAT!