When our mind ''knows'' something, it doesn't see the need to focus a lot of attention on it anymore. If you have had certain beliefs for a long period of time, you have grown so accustomed to them running your life that you don't even register they are there anymore. This is great if all of your beliefs are completely empowering and are continuously improving the quality of your life. In my experience however, everyone, and that includes some of the most successful people in the world, have beliefs they can change or tweak in order to improve their lives.
Most people have a lot of negative and self-defeating beliefs they are completely unaware of, and because self-mastery is a continuous process and not a destination, there are always positive changes to make. We are constantly thinking the same thoughts and entertaining the same beliefs. As a result, we are manifesting the same experience of life again and again. Studies show that up to 90% of what we say, think and do is the same that we have said, thought and done the day before.
The Mind-Made Prison: Radical Self Help and Personal Transformation by Mateo Tabatabai