You can easily check this yourself and you will see it is true.
Choose a word and repeat it over and over again in your mind, until it becomes a habit.
You will see this word, or a related word pop up in your world again and again.
And then you can even change the word when it pops up and you will see this variation in the same way as the word before.
For example if you did what I explained with the word “study english” you will see this term in your life. And if you change the word when it comes up to “Stanley English” for example, you will, to your bewilderment, see the name Stanley over and over again in your world.
Don’t take my word for it, try it.