The best way to self discipline that I've found (and I'm still working on it) is to learn to do something that our culture has taught us is yukky, gross, and unacceptable: Learn to love yourself.

Give yourself every advantage in life (not ever at the harm of other people); for the body, healthy food, for the mind, intellectual stimulation in an area that interests you (for example, for me it's people, computer programming and music), and or the soul, laughter and contact with good people.

Loving yourself has received such a bad rap in society but it really is what God wants us to do, and his model emotion for that is this: Don't you want your children to care about (love) themselves and to give themselves every advantage they can have as well? Of course you do.

Also, when you do accept, like and love yourself, you are much more well equipped to love others. You will also inspire others with your life and help them realize that it's really OK to take care of yourself, and as an added bonus, self discipline comes (more) easily.