Setting a boundary and not enforcing it is worse than not setting it in the first place.
Think about it:
The next time you think about making a serious request of someone or setting a new boundary, think carefully about what it will really take to enforce that boundary.
Because if you don’t, you’re training the people in your life not to respect you. And worse, you’re destroying your self-respect. Both of which will lead to a lot of unnecessary emotional pain and mental stress.