You need confidence AND willpower. As you wrote, willpower implies you are consciously working against your own natural instincts to do something that you think is best for you. The problem is in your own natural instincts. Especially in the beginning of your "career" as trader. Subconscious is very powerful and works without you noticing it. It is an automatical reaction. So in situations were you are distracted, or have to take a very fast decision, your subconscious will overrule your conscious. You need time and have to train your brain to stop your automatical and subconscious reaction and replace it with the conscious reaction that should be executed.
For the rest I agree completely with your posting.
A good example of this power of subconscious is that people can learn how to react if they lose control over their car while driving. Following their natural instinct is always a bad solution, so they have to learn what to do and what not to do. And apply it immediately when necessary. Especially that last thing is difficult and can only be changed by training a lot.
How do u train your brain or sub conscious to do the right thing? Is it by repeated experience and u hope the brain 'gets' it?