Focus on the prize :) [Whatever your ultimate goal is: whether it be modeling, your children, etc]
Use sticky notes if you have to [put them everywhere], journals, a diary. Make realistic goals and follow through. If you have to mark your daily goals on a calendar and check them off one by one as you complete them, do that.
And remind yourself that every time you don't follow through you are only cheating yourself out of the good, healthy life that you deserve :)