Build on the willpower you already have.
Every successful person has a fair amount of self-control – it's just the nature of success. And since you have the formula for discipline, it's easy to change the activity and apply it to other parts of your life. If you can get to work on time every day, you're disciplined enough to get to the gym regularly or to cut back on the refined sugar in your life. And then, rather than trying to change everything at once, build on the small victories you've won and implement new changes incrementally.