Self-discipline as a whole is not more complicated today than it was thousands of years ago. Get yourself a notebook and keep an hour-by-hour program of all your daily activities. Not just the important things, but also trivial tasks. Plan everything, even at what hour of the day you'll brush your teeth or what pages of a book you'll read after lunch. Go Immanuel Kant at first, and when you can approach all your necessary tasks with more ease, then you may relax a bit.
Eat well and light. It's astonishing how much of a difference diet makes, but it's true. Eat lots of fruits, cereals and vegetables, cut on the meat, bread and salt (or just leave them completely). Couple this with two days a week of intense exercise, or just half an hour of brisk walking each day. After two or three weeks you'll feel more energetic and mentally alert.
Never procrastinate on your daily obligations and tasks, but with bad habits do the opposite. If, say, you're a compulsive mp3 downloader, then on the next time you feel the urge to download an album, instead you will annotate the name of the album in a text file and keep it filed on an "albums to download" directory. If you always do that, you'll be less urged the next time you feel like downloading an album. This method might seem kind of silly when read, but it is with small, trifling habits such as this that your self-discipline demon is nurtured each passing day. Be consistent, and before you know it you will be able to do things you never thought possible, like writing novels, music, bodybuilding, or whatever suits your fancy.