I'm pretty disciplined but it can take a while. These things just take time. Find yourself a routine and STICK WITH IT. Log it. Tell people. (social accountability xD) Join sites that help. Do the research. (there's a LOT of research to be done) Make it part of your life. Diet, for example, shouldn't be a "diet" (healthy eating, basically), it should be a life choice.

I suppose you could start with something small, keep at it, and when you succeed, start with something a little more, and so on.