Saying no, and saying the hard thing

A yes you did not mean costs a Saturday. The no you did not say would have cost four seconds. Everyone agrees with that sentence and almost nobody acts on it, because the four seconds are now and the Saturday is in three weeks, and the part of you doing the deciding cares enormously about the difference.

So the books do not tell you to value yourself more, which is advice with no handle on it. They go at the specific beliefs. That a no needs a reason good enough to survive inspection. That refusing is a small unkindness you are doing to someone. That a difficult conversation gets easier with time, when in fact it sours: the thing you could have said plainly in March has to be apologised for by June. That asking for help puts you in debt, or shows you cannot cope — which is never how you think about it when somebody asks you.

There is also the flat practical problem of what to actually say, at the moment, out loud, with the person standing there. Both books end with words you can use, because "set a boundary" is a goal and not a sentence.

Being the person everyone asks is not a personality trait you were born with. It is a reputation, built one yes at a time, and it can be revised the same way.