When boundaries feel rigid.
When someone respects your boundaries it usually only takes one or two times of them bumping up against your boundaries before they adjust. Eventually, those boundaries feel effortless for you.
If, energetically, it feels like you’re using all of your strength to hold your line, it’s because the other person doesn't care about your boundaries. You're not being too rigid, they're not respecting your line in the sand.
Take note of the difference.