What is self-discipline?
To my understanding, self-discipline requires a strong willpower to do something which is right and meaningful in the long run.
It also reminds me of the famous "Marshmallow Experiment" which meant to reach "delayed gratification" by our self-discipline.
Actually it's quite challenging when we are in face of various temptations and interruptions externally or internally.
So I think it's better to find the sweet spot between "the ideal and real self-discipline". Occasionally, a bit of indulgence or a small reward for ourselves especially after some progress or improvement.
Never push ourselves hard. Don't go extreme and blame ourselves when we fail to do something that we should have done. No one is perfect.