I know it's a joke, but to make a serious point off the back of it:

There's no such thing as willpower.

There's motivation, and there are habits.

If motivation is lacking try adopting micro-habits, especially if off the back of something you can monitor (thank you AppleWatch and MyFitnessPal).

“Every habit and capability is confirmed and grows in its corresponding actions, walking by walking, and running by running… Therefore, if you want to do something, make a habit of it.” - Epictetus

And when the inevitable falling off the wagon happens...

https://youarenotsosmart.com/2010/07/07/extinction-burst/

Psychology graduate with interests in values and morality, cognition and executive function, and High Functioning Depression. Kiwi living in London, UK.