What you refuse can protect what you already chose.

A commitment made and then undermined by everything you accept afterwards is not really protected. Every refusal is a way of defending what you already said yes to, and people who cannot refuse tend to lose the things they most wanted, not through a decision but through erosion.

When declining something, remind yourself what the no is protecting. Naming the thing makes the refusal easier and more accurate. It also stops it feeling like a rejection of the person asking.