Self-discipline is usually described as willpower: gritting your teeth and doing the hard thing anyway. That description makes it sound exhausting, and exhausting things rarely last.
During my engineering studies at the Mohammadia School, I tried for a while to push through study sessions on willpower alone, staying at my desk through fatigue and distraction. It worked for a few days, then collapsed. What actually lasted was something less dramatic: a fixed study block at the same time every day, in the same place, with my phone in another room. The discipline lived in the setup, not in gritting my teeth each time.
Willpower is a finite resource that depletes through the day. A system you have already built does not ask anything of your willpower, it simply tells you where to be and when.
If you have tried and failed to be more disciplined through sheer effort, the problem is rarely your character. It is more likely that you are relying on willpower for something that should be running on structure instead.
Pick one habit you keep failing to maintain, and instead of promising yourself more effort, change one thing about the environment around it.
