Brain 1 is the one with long term planning, analytical skills, slow and logical thinking, not impulsive, patient and calm and calculating
Brain 2 is powerful, impulsive, it feels the body and environment, its reactive, it perceives
There is a moderation of brain 2 by brain 1 in every given moment. Consider this - i see a very tasty ice cream being sold on the street - my immediate reaction is to somehow eat it, i want it. My analytical brain pushes on this and tries to convince brain 2 by comparing the current ask with the goal - healthy diet, expense, impulsive behavior and so on. This goes on throughout the day and there are multiple suppressions which tax this control and over time - by the evening brain 1 starts to lose this control and become less analytical and more impulsive
I think meditation is the act of observing brain 2, brain 1 and even this modulation in action
Our duty is to observe these triggers by the environment and moderate not based on a rule but our understanding of that rule. Pain that is worthy of some higher goal is not pain its just an obstacle.
Sometimes when you take a top down decision, there is less need for moderation - eg i will eat in the evening