The Anatomy of a Boundary

A boundary has three parts: the need (what you require), the communication (how you express it), and the consequence (what happens if it's crossed).

The consequence doesn't have to be dramatic. It can be: "If the yelling continues, I'm going to leave the room until we can talk calmly." Then you actually do it. Consistency is what turns words into boundaries. One follow-through teaches more than a hundred conversations.