Ruiz speaks of the many beliefs and agreements that we learn or are imposed on us as we navigate the world.  Many of these beliefs become what we know and sometimes limit our happiness and success.  For example, as a child if your parents negatively criticized your drawings, you may have this internal believe that you are not a good artist and thus never pursue improving your craft.  There are many people earlier in our lives that may have imposed limiting beliefs without us or them realizing.  It's one word or one sentence that we unconsciously tacked on to.  Ruiz calls us to take a look internally and review how we interact with ourselves and others to find these limiting beliefs or personal agreements.