The guilt isn't evidence you're wrong.

Not into confidence, and it's worth being straight about that — confidence follows evidence, and evidence takes repetitions. What seven days can do is give you a few usable phrases, get you through several real refusals in low-stakes situations, and produce a written record of what actually happened. That record is the point: for most people the feared consequence doesn't arrive, and without writing it down, memory keeps the old prediction intact.

Usually it isn't a skills gap — you know how to form the sentence. What stops you is a forecast: they'll be angry, they'll think you're selfish, the relationship will suffer. The useful thing about a forecast is that it can be tested. And the agreement itself typically happens in the first three seconds, before any thinking, which is why the most effective technique isn't courage but delay: "let me check and come back to you."

No, and giving one usually makes it harder. Every reason becomes a problem for the other person to solve — "I can't do Thursday because I've got something on" gets answered with "what about Friday?" A refusal without a reason is shorter and considerably harder to argue with. Choosing to explain in a close relationship is fine; the point is that it's a decision rather than an obligation.

Different, and anyone telling you to just say no to a manager is ignoring how work operates. Flat refusal carries real risk. The effective form makes the trade-off visible instead: if I take this on, which of these moves — what would you like me to deprioritise? That's a refusal in substance, and it's usually received well because it treats the constraint as shared rather than as your problem to absorb.

Some people will, and that's information rather than proof you did it wrong. A reasonable person adjusts when told no; someone who escalates, sulks or punishes over a single refusal is telling you something about the relationship. Separately: if refusing a particular person has ever left you frightened, or you adjust your behaviour to avoid their reaction, that's a different situation — assertiveness practice isn't the right tool, and support services exist for it.