Boundaries are scary, aren't they?
"What if I hurt their feelings/upset them?"
"I don't want to be mean."
"I can't. They always do XYZ for me so I have to do ABC for them."
"What if they leave?"
"I don't want to be a selfish person."
Committing to boundaries seems great, in theory. The empowerment. The self-love. The ability to have healthier relationships where you feel respected and valued. Including (and most importantly) the relationship you have with yourself.
In practice, boundaries can be a different story though, can't they? They can be scary, difficult, painful, exhausting, and even dangerous depending on the situation you're in.
But learning to establish & honor your boundaries - like anything else - is a skill.
And the way to handle any skill is to develop a practice of that skill so that it strengthens over time.