One of the main reasons that a lot of people seem to have difficulty in being successful at doing certain things or obtaining certain goals is because they do not know how to self discipline themselves or that their self discipline is in need of improvement. When a person increases their self discipline then they will have more control over certain things in their lives and their life becomes more productive.
Before you can gain more self discipline we need to be able to acknowledge the fact that we need to improve upon this in our lives. If we don't realize that this is where perhaps our problem lies then it is going to be nearly impossible to improve upon it. Unfortunately the average person won't usually strive to improve self discipline until they realize they're in trouble.
The first thing you need to do is to set goals for yourself that are truly obtainable. Your goals must at all times be realistic. If your goals are not realistic then you are going to only continue to take steps backwards and you are setting yourself up for ultimate failure. Setting goals way too high will definitely help aid you in failing and then this in turn is going to be the proof you needed to tell yourself you couldn't do it anyway. On the other hand though, if you set for yourself some smaller goals which will help you reach the bigger goal you more than likely will be able to keep moving forward.
In order to improve upon your self discipline you are going to have to agree to change your habits. If you have bad habits, they are only going to eventually get in the way of your self discipline. For example, if your goal is to lose 20 pounds, it's not going to happen if you find yourself raiding the refrigerator every single night at midnight. But don't cut the habit out cold turkey. Start cutting the midnight raids down to 4 nights, then 3 nights, to 2 nights etc. until you are no longer doing it at all. This way, you will be able to reach that bigger goal without back stepping during the process.
Another good example is if you are a person who tends to abuse alcohol whenever you are around it, then remove yourself from it. Don't hang out at places that serve it and don't hang out with other people who are heavy drinkers either. Remove the problem and you won't have to deal with it.
Make sure that you find things that you know need to be done on a daily basis but you avoid doing them. For instance if you know that sleeping four hours a night is not what you should be doing, then make a conscious effort to make yourself go to bed a couple of hours earlier every single night. Creating good habits makes it far easier to be self disciplined.
Make lists or plans for daily activities. Don't just start the day off with not knowing all the things that you need to get done. Instead sit down the night before or first thing in the morning and write down all of the things you would like to achieve for this one day. Again, be realistic, only list as many things as you can handle in say an eight hour time period. Don't go over that amount of time or you may procrastinate and get nothing done.
Final Note: When you feel you've have accomplished something because of good self discipline, then guess what? Reward yourself for a job well done. For example, rent a movie, read a good book, treat yourself to lunch or dinner. But do reward yourself, you'll be more willing to continue to try to improve your self discipline if you do.