Boundaries have been a useful concept in relationship psychology for some time. They create a barrier to keep unwanted people out of your personal space. (See upper diagram.) The circle represents the boundary that keeps other people away from the person or "P". 

Parameters define the relationship or the interaction. They create "ground rules" for the relationship or interaction. They say when we interact you can go here, but you cannot go there.  (See lower diagram.) The area inside the curved lines represents within the parameters of the interaction. The two people or "P's" have an unobstructed, open space to interact. The area outside the curves lines is outside of the parameters of the interaction and the person that you are relating to is not permitted to go there.

Is it half-full or half-empty? Do you focus on the people that like you, or the people that don't like you? Do you focus on the 10 positive things in your employee review, or the 1 negative? Do you focus on the things you have, or the things you don't have? Many of us focus on the negative. We have a "propensity of the negative."

Why? The negative resonates with our negative self-belief system- that thing that tells us that there is something wrong with us- that we are deficient in some way. Then we project that negative view onto people and situations.

And... negative choices are reinforced easier than positive