This is something I am still very actively working on, but I did have a lightbulb about it a few weeks ago.
Not a boundary: if he doesn't have a job by the end of the month, I will leave him.
Boundary: I will only be in relationships where the partners are equal and both contribute equally.
I am not sure my boundary is 100% on, but notice the shift ... Not a boundary -> someone else has to do something for me. A boundary -> I do something for myself as I am the only one I can control.
Just got this a few weeks ago and it took me a while! And I still need to work hard at applying it across the board.
Hope this helps.