What's the difference between knowing and doing, in your trading?

Every beginner knows the rules they keep breaking: don't move the stop, don't average down, risk 1%. Knowing is cheap; doing is the whole game. The gap between them is where accounts die.

How do you close the gap?

• the rule you knew but kept breaking
• what finally made it stick
• how you practise discipline like a skill

The psychology category is dedicated to this gap; this thread names it plainly.