Willpower, strength, determination, fortitude, resoluteness - call it what you will, but most people need it to overcome both the physical addiction to sugar and it’s effects, in addition to the psycological and sociological ties to desserts and bread, often with extreme pressure from the outside to keep imbibing.
This is the struggle my sis inlaw has been failing at ... until she joined the Bright Line program. She literally did not have what it takes to commit to a healthy WOE despite obesity, diabetes, arthritic pain and many other problems.

For myself, like others here, no extra ‘willpower’ was needed, I feel my success has been due to simple patience, and I found it easy to love low carb food choices and to be further encouraged with positive results, but I can see that is not even close to the truth for my sis inlaw. She is losing weight steadily now and more power to her for finding a program that can provide her with will to stick with it.