I demonstrate this in group presentations.
First I have a person imagine the face of someone they have unresolved conflict with on an object I am holding in my hand such as a water glass. I ask them to feel the emotion of the anger or disgust.
Then I ask them to close their eyes and continue imagining the face of the person on the object.
Next I merely move the object to the side or toward them. Even though I am 10+ feet away from them their physical bodies move in what ever direction I move the object they are focusing upon.
I am showing how their anger is attaching them to the object I am holding and how that anger is allowing the object to control them.
The same is true when we are angry with an individual. We are attaching ourselves to them and giving them control over us.
Forgiveness sets us free.
This is why Jesus instructed us to resolve conflict with our brothers before we come to worship.
If we have attached ourselves to someone else, we are not free to attach to Jesus. If you have someone else on your mind it is difficult to even think of Jesus.
Often the anger is that strong it knocks the person off their feet when I move the object.