The mind

It's convenient to think we are in control of our mind.  That we, are the speaker.  In reality, we are just the minds audience. 

Our minds have less effect on the world as we know it.  What our mind actually affects, is our feelings about the world, not the world itself.

If we want to know ourselves, we will get familiar and observe the chatter happening in our minds and its effects on the quality of our motions.