People who benefit from your lack of boundaries will call your new ones “attitude.”

When a limit arrives, the loudest objection tends to come from whoever was getting the most out of there being none. Calling it attitude makes the problem about your tone instead of about a lost convenience. The complaint is often sincere; they really are inconvenienced. That still does not make the limit wrong.

Expect the pushback rather than being startled by it, and keep your voice level so there is nothing to point at. Hold the same line a second time. The second time lands differently from the first.