If you get in a room with me these days, you will hear about Brain Science 101, I am really passionate about it. When you truly understand something, you can change it, if you choose to.
From the time we are young, our brain develops associations to its environment, so each memory we make around a thought, we associate it with feelings, emotion, other people, and other thoughts, so what we think about anything comes with a whole lot of attachments. Our mind doesn’t know the difference between fantasy and reality, so all of the associations we have around the thought make up a truth.
It may only be what we have perceived to be the truth but for our brain, it's the truth. Therefore you cannot disagree with the truth.