Willpower is overrated. The person who keeps junk food in their kitchen needs more willpower than the person who does not. The path of least resistance usually wins.
Environment design is behavior design. Make good choices easy and bad choices hard. Put the book on the pillow, not the phone. Keep the workout clothes visible, not buried in a drawer.
You do not need more discipline. You need better defaults. When the environment supports good behavior, good behavior becomes automatic. When it supports bad behavior, you fight yourself constantly.
What environmental change would make your desired behavior easier?