Knowing what you need and actually saying it out loud to another person can feel very different. Many people who struggle with limits understand them conceptually but find that guilt, fear of conflict, or worry about being seen as difficult gets in the way when it matters. Often this has roots in earlier experiences that taught you it was safer to accommodate than assert.
Therapy focuses on both the understanding and the practice. You will look at where your patterns around limits came from, what makes asserting them feel risky, and how to communicate clearly without it needing to become an argument. That often includes working with the actual language of direct communication, not just the theory of it, so that the words come more naturally when you need them in real situations.