You don’t take them under consideration, you DEMAND them.
My experience has always been setting boundaries but allowing them to be flexible depending on the person. As of late I no longer allow my boundaries to bend. It is a healthy standard for my life and how I aspire for my relationships to flow. By having boundaries, you have now set the precedent of acceptable behavior and respect. People only cross boundaries because they believe that they can, that they somehow reserve the right to because of their position in your life. Lack of boundaries invites lack of respect.