The brain of human being is split into two parts The Conscious and Subconscious.
@ Conscious mind : Responsible for logic, Calculations and all actions that are perform while you are Conscious.
@ Subconscious mind : Store all of your previous life experiences, your beliefs, Your memory, your skills and control other function in your body like breathing and hearts beats
Example:
When you learn a new skill like riding a bike or driving a car, you can start off by doing it all at a Conscious level. Then, through the natural process of trial and error, you eventually learn the skill so well that it become a habit that you can perform without having to Consciously think about it. This is just on example of how your Subconscious mind works.