I think it's just practice. I used to be an internal monologue reader into my 20s until I worked to not be one(because I wanted to increase my reading speed). Maybe I was neurally set up to achieve this - I am strongly left handed and have been told by many people they dont understand my thought process on things(not in a bad way, just sort of "where the heck did you come up with that") throughout my life.
Just start looking at text and don't let yourself say the words in your head.
Just start looking at text and don't let yourself say the words in your head.