If you say yes to everything, your yes stops meaning anything. Leaders protect the value of their word.

Agreement is only informative if refusal is possible. Someone who says yes to every request has told you nothing when they say it to you, and their commitments become a queue rather than a promise. The value of an answer comes from the fact that it could have gone the other way.

Say no to one thing this week that you would normally absorb, and say it early and plainly rather than by going quiet. You do not owe a long justification. Then put the recovered hours into something you already said yes to.