At the beginning, when you’re struggling between old habits and new habits, if your willpower levels are low, one thing that can help is self-affirmation. Think of someone or something that’s important to you. So when you’re feeling weak and tired at the end of the day, this can help boost your self-control. Leave little messages where you can easily find them like on the refrigerator, or near the door, or on your doorstep, to remind yourself of what you’d like to change.
Pre-commitment is quite handy. What you do is try and think ahead to times when you’re going to be tempted to follow your old habits, and think of how you can commit yourself in advance to your new habit. So if you’re trying to avoid using Playstation, you can give the controls to a friend so that you won’t be tempted. When you’re feeling strong, you make a decision so that when you’re feeling weaker and more susceptible later, the temptation will be gone.