Discipline is easier when it’s clear. That’s why the Stoic writings are filled with rules and reminders. About what they do, what they don’t do, what they know is unvirtuous.
In moments of temptation, “I probably shouldn’t” is not a great line of defense. But knowing what you do and don’t do? Much better. Try to turn down a slice if you’re someone who “usually doesn’t eat carbs.” When it’s right there in your face, you’re not going to be able to say no. This is why 12 Step groups insist on total abstinence. The slippery slope is too dangerous.
Make clearer lines. Define who you are and what you do. Free up your energy for other considerations. Let your discipline be set in stone.