"Boundaries are the distance at which I can love you and me simultaneously".
~ Prentis Hemphill
One sign that we value and respect ourselves is healthy boundaries. For example, we don't allow a family member to speak rudely and throw insults at us, or we don't allow an overspending friend to constantly borrow money from us. We protect our personal space, our time and energy, so that we don't feel taken advantage of.
People pleasers are for example the kind of people who don't have healthy boundaries, because they're afraid that if they say No, they will be rejected. They feel obliged to accommodate to everyone, not paying attention to their own needs and desires. It often takes them to get sick before they start taking care of themselves.
The other extreme is when the person is unwilling to help others or do someone a favour, because they feel threatened or inconvenienced by it. Or, if someone is very reserved, afraid to open up and doesn't trust people. Those would be examples of too hard boundaries.
In order to have personal power, our boundaries should be flexible. This means we're open for contact and welcoming, but at the same time we are able to protect our space if necessary.
People with healthy self-esteem usually don't have a problem maintaining healthy boundaries. They know when to say Yes and when to say No. They welcome loving, supportive relationships and minimize the toxic ones. They gladly help others, but protect themselves from those who would like to misuse their goodness. That way they can enjoy their relationships, without feeling overwhelmed or taken advantage of.