Assertiveness is the ability to set healthy boundaries by confidently standing up for your own rights, while also respecting the rights of other people.
Remember that if someone behaves in a toxic way, it usually says more about them than about you. If you take it personally, it is like agreeing with what is being communicated, and as soon as you agree, the poison goes right through you.
You can train yourself to remain calm and confront others assertively, even if you need to tell them that you are very upset by their behavior. Make a decision that you will not respond aggressively and will also not be submissive and let them get away with the toxic behavior. Some useful communication techniques are described in the subsequent section.
Moreover, realize that the aggressor might not be a bad person. Hold the attitude that they behave this way because they care about what you do, not because they want to make you feel bad. It is simply their unskillful attempt to give useful feedback, or maybe they are just having a bad day.
Acknowledge that you might play some role in the problem. Get curious and search for the 2% truth in what you are hearing. Express an interest in the other person, and ask questions to find out what they are observing, feeling, and needing. When you do this, you might find that you can have a real dialogue with them and work through the problem together.
Sometimes criticism might also help you to identify behavioral blind spots, i.e., things that you don’t notice yourself, but which other people notice, such as the unintended impact of facial expressions, body language, tone of voice, etc. Take responsibility for your behavior and apologize when appropriate.