For instance visitors want to stay for a period of time (not a weekend) you don't want them to but find yourself saying yes. Having work done and the people doing the work take far longer than agreed but you don't say anything. People who generally ask you to do something for them that you don't want to do but you can't say no.
As someone who dislikes conflict or confrontation of any kind yet also doesn't have a problem asserting my boundaries politely and saying no I genuinely would like to know what stops people who say yes but want to say no from doing so.