The request that comes with a real choice is easier to receive without defensiveness.

A request with no real option inside it is not a request; it is an instruction in polite clothes, and people feel the difference immediately. When declining would cost them something, they answer defensively, agree without meaning it, or start managing you instead of the task. Genuine choice is what makes a yes worth having.

When you ask for something this week, say plainly that no is an acceptable answer, then behave that way if it comes. Give the information needed to decide rather than the case for agreeing. Notice whether people ever actually decline you, and what it means if they never do.