Your "boundaries" feel like shit.
Here's the thing about boundaries.
Real boundaries rarely require a follow up of "I'm just holding a boundary."
Boundaries exist at a deeply intuitive level. They are often not voiced. They exist so deeply and so intuitively that other people instinctively follow them. It is, truly, a vibration that we emit out into the world, that comes from our core.
When it's clear we are lacking in boundaries, the work is not then to "activate them" or to "take action" - the work is to remove all the layers we have standing in the way of our intuitive boundaries being felt: our preferences, our fears, our judgments, our negative or limiting belief systems, etc. It's in doing less, not more.
Walls, on the other hand, require justification and defense.
Walls exist on the premise that we require protection from some evil force that exists outside of us, that will betray us, take advantage of us, poison us, or otherwise misuse us.
Walls imply that we will not be cared for, and that people can make us feel bad, and that we are powerless against that.
Books on boundaries, and healers saying you need better boundaries, or that you need to be protected because you're hyper sensitive or deeply empathic (without the follow through of explaining this essential piece), have a flaw in their approach. If we systematically apply "boundaries", what we're actually doing is protecting ourselves from places where we still require healing.
To put up a wall effectively facilitates our own spiritual bypass and prevents us from healing.
A boundary exists by default. It is our intuition. We all have intuition in there, somewhere. When we are in integrity with our intuition and are honoring what is true for us, it feels GOOD to other people, and CREATES connection. When we are putting up a wall, it creates angst, strife, and disconnection.
NB: Yes, sometimes physical boundaries are necessary to heal. And usually it's our intuitive boundaries that facilitate us claiming the physical boundary, first. The boundary that was acted upon is that we followed our intuition to leave. Not the actual act of separation.