?

If you saw the brain the way Iain McGilchrest sees it, the corpus callosum dividing the two hemispheres might make that physically and psychologically impossible. The gist of it is that the left hemisphere controls focus on specific items in a mental image. The right views the overall picture. The corpus callosum both inhibits and processes output from the two sides. For example, the corpus callosum won’t allow the left hemisphere to remove the focus of the left brain when it is working. It will, however, allow information received from the left brain enter the right brain to be added to its picture of the whole.
Could it be possible to master the mind? Probably not if this means the left brain must master the right. The corpus callosum won’t allow that.

[brainworldmagazine.com]

He also has very interesting lectures and discussions on YouTube.

I truly believe in mind over matter. There are very few things that I can't control my reaction to. I have a superstrong willpower and I'm stubborn as hell, so I think I have my mind pretty much mastered, lol

See if you can count to ten without thinking of a "dirty word." If you can't, then you haven't mastered your mind.

I don't think he is accurate. Nobody can be a complete master of their own mind. There are too many factors we have no control over for that to be true, especially genetic factors.

most of the time yes but psychotic episodes show me thats not always possible

Not sure I understand the question.

I don’t know about “completely” but all learning contributes toward a kind of mastery of the mind. The usual message in that sort of talk is that you can’t always control external circumstances, but you can, with some practice, learn how to control how you respond to those events.

I’m completely crazy lol. There’s no controlling my mind

A motivational speaker said....

The thing that has helped me the most since becoming atheist is learning how I think and how my background informed my thinking. It has been very empowering to choose how I think. It is definitely something I have found to be worth while.

And that's your mind telling you that. Oh the grand deception.

It's hard for me to say about if that is true for most people or not.
For me it's not something I can't do. I have schizo-affective disorder.
Which means I hear and see things that are not really there.

Through medication, and therapy I've been slowly getting a little better. I have to take baby steps to try and change how I deal with that. but there is no cure. So mastering my mind is not really an option for me.

Hahahahaha

Like most answers, in some things yes in others no. Your brain creates many of the rules and structure that you would use to "master your mind". What happens when one of the things you want to master is literally the structure that you'd use to make the change.

Imagine having a screw that you need to screw in, but it's on the handle of the screwdriver.

That's definitely an overstatement. Most people do have a great influence on their minds, but complete control? No, surely not.
An easy way to disprove this claim is this. Try to stop yourself from seeing red. Or try to make your vision go upside down. We know that our brain is in principle capable of things like this. If you can't control this aspect, you don't have full control.
To be fair, if you want to motivate people you should probably tell them that they have control over their lives and you have to tell it in easy terms. Something that is catchy and easily repeatable. So I don't think that these statements were done will a deceitful intention.