I have the theory that there is no such thing as "willpower".
I do not know if it is so much that it does not exist, but I do not like the concept because it puts responsibility outside of one and it is also deceptive. People speak of willpower as if it were a kind of gift given by a higher entity that some have been lucky to receive and others have not. It is common or read or read phrases like:
"How lucky, I would like to do the same, but I have no willpower"
That's comfortable to excuse yourself but if you think about it coldly, do you really think it's true? What is really what you do not have? Is it that you were born without something that others have? Have you done anything to offend your gods and deprived you of any gift?
When you say willpower, do you mean the ability to stay firm in your decisions and not always fall into what is easy or more palatable at the moment? I think so and for me that is not a matter of mystical strength. It is a question of clarity, determination and coherence.
I discovered this when I was training my first 10k race to get out of a depression. It was crazy for me to train five days a week, strict diet and face the demon of depression. At first I complained about the willpower that was needed to achieve it, but after a few weeks I began to change my mind. I realized that day after day, what was really happening was that I faced myself and said:
Let's see, if you're not going to train, does it bring you closer or away from the objective? If you move away, what could happen? If you approach, what will you have achieved? And then, it's just a matter of being consistent with your own decision, accepting it and moving on. Take the necessary steps and be aware that you choose to get it and renounce not doing it.
That's why I say that the recipe is not based on willpower, but on a plan based on three steps:
Be clear about the objective you want to achieve. Establish it with absolute clearness and so that the result is measurable and evaluable. If possible, with a specific execution time.
Nowadays I would say in order to achieve what you want to, focus on becoming the person who would behave liked, as explained when I wrote about the book "Atomic habits" here.
Once the objective has been established, analyze the steps that have to be made and accept to make them even if any obstacles are placed in the way. No matter what.
In the day to day appear a thousand situations in which one has to take steps that are approaching or moving away from the objective. It is time to observe them closely, evaluate them and be consistent. Have I decided to take a path? Great, I decide to be consistent with my values, my principles and decisions and move forward. I make the decision not to cheat or give up myself
In the end it is a matter of responsibility. You act in a mature way and assume the victory and defeat of your own struggle. When you act like this, it is not so important if at the end of the path you do not expect absolute victory, but each step you have given it by your own decision, without surrendering to the ease of the moment. Freedom and autonomy after all.
Anyway, as I said, if you are trying to build a new good habit or get rid of a bad old one, go back to the masters like James Clear. They will tell how to actually walk the path of that thing we sometimes call willpower.