Healthy Boundary
A healthy boundary is a clear limit on what you will and won't do, give, or accept, stated plainly and held without aggression. It protects your needs while staying open to the relationship.
Picture being asked to take on a fourth project when you're already underwater. A healthy boundary sounds like: I can't take this one, my plate is full. No long justification, no apology marathon, no slammed door. Just the limit, said once and meant.
A boundary protects your needs and keeps you in the relationship at the same time. It is not punishment or a test. You name what works for you, you let the other person have their reaction, and you don't rush to fix their disappointment. The clarity is the kindness, because guessing is harder on everyone than a plain no.
For a people-pleaser, the hard part is the guilt that follows, not the words. That guilt is a nervous-system alarm, not evidence you did wrong. It tends to crest and fade. A healthy boundary often feels uncomfortable at first and steadier each time you hold one.