I feel like I understand this lesson. And have for a long time. But I still keep falling for it. If someone can bridge that gap between intellectual understanding and practical action for me, I would appreciate it greatly!
Okay, so your 'target behaviour' is getting involved in frustrating arguments online and the behaviour that arise which cause shame in the future.
The first step is to gather data, which is a journal. You want to record all the little daily things in there because that will help to inform you about your vulnerabilities. Willpower is a finite resource and that is proven with repeatable experiments. So if during your day you're experiencing difficulties, that will sap your control for later in the day.
The second step is to take some regulation skills on board, which are a bottom-up sort of thing. Hygiene, physical health, a clean living space. Mindfulness is a necessary practice and another thing you keep track of in your journal. Mindfulness is a skill you build through practice, and eventually it will translate into direct emotional awareness and active self-observation.
The third step is to start recording in EXCRUCIATING detail everything that lead up to the behaviour you wish to change. Where you were, what was said, what you felt, what you did, what you felt after, etcetera. Stick only to literal facts for this part.
Then you're going to take all that data and use it to make small changes in your life which will reduce the drain on your willpower/emotional stamina. I am not done sculpting my behaviour by any means, and I noticed that the activity really resembles what I was doing when I trained my cat to give me high fives for food. Because, when you exhibit healthy coping mechanisms and you don't engage in that argument and you don't have to cope with the shame after, you reward yourself. Just like my cat. It's working for me.
One thing I think I realised through all this, is that "we" are our attention. We are not in control of the hugest majority of our personality aspects. They come from our genetics, from our upbringings and past, and from our current contexts. But we will always have the ability to decide where we direct our attention. That is where agency lies. If there is a soul, that's where it is. That's who we are--our conscious attention. The rest of the mind does its own thing--just try observing your thoughts sometime :)