That was a conclusion that Napoleon Hill came to, after interviewing the most successful people in the world. He stated that controlling the mind was the only thing we have control over.
Do you believe you are controlling your mind when in fact you are not? Are you merely along for the ride and watching helplessly as your thoughts respond to the stimulus of the day; or, wander aimlessly without direction?
Key to all of this is practice. Practice controlling your thoughts. With that practice in silence, you can learn to use the skill in life.
I find it very rewarding to stop myself from thinking that would harm me emotionally and switch the thinking to something that leads me to Truth.
However, to accomplish things in life we must convert thought into reality. If the reality I want to create is emotional, the activity I must do is to really analyze my thoughts and re-wire the brain if necessary.
How do you do that?
You do it by questioning the beliefs that you already have. Look for evidence that you are wrong. Look for truth.
I have had people tell me that they can switch their minds to positive thinking. Yet, as I watch their behavior, I question whether the positive thinking is reality for them.
For example, if something disappointing happens, many people will become depressed. That is one response. Another is to say, something good will come of that. That is another response but is only slightly better. Even better is to LOOK for what good can come from that. I am not saying the process is easy. I am saying that it is essential.
Fame and fortune will not guarantee happiness. Evidence of that is all the celebrities who commit suicide or become addicted to drugs. Learn to control your mind and re-wire your brain to find happiness. Then, seek whatever else you desire.