What is important to remember is that there is a big difference between boundaries and ultimatums. Firstly we need to remind ourselves that we can only change ourselves and not others, which is why setting ultimatums rarely works, because the essence of an ultimatum is to change the other person.
Setting boundaries however is about changing our own lives, deciding what we want in our life and what we do not want and enforcing that regardless of the other person. What I mean by that is that we may decide that the boundaries we want in our own life is peace, tranquillity, harmony, love, safety, security. We can make a pledge to ourselves that we will only allow people in to our lives that are supportive of those boundaries we have made for ourselves.
We can give those that are not supportive the opportunity to be part of our lives by giving them the choice to set the same boundaries in their lives as we have chosen in our lives, but we can’t force them to do that. What this means is that we can inform them of our own boundaries and let them choose whether it is something they desire too and if not then they are not someone able to be in our lives.
The important thing about boundaries is always to remember that it is about us and not others. We have to be decisive and active in setting and maintaining our own boundaries. This may mean we have to learn to detach emotionally from people who have no interest in sharing the same lifestyle/boundaries we have set for ourselves or can not at least respect our boundaries when in our presence.
Of course we must remember not to have double standards either, because the whole point is that boundaries are what we set for ourselves and not others, which means that if we expect calm, peace, tranquility, harmony, stability, security then we have to be the ones to create those values in our life, unlike an ultimatum that you might set someone else.