You can “harden your heart” in order to protect yourself from being emotionally injured. As to how it is done, that is usually a matter of advance decisions, and self-discipline. You decide in advance that you will do a specific thing, or will respond a certain way, and then in the event, you steel yourself to actually follow through.

In defensive “hardening,” you anticipate that you are going to feel a great deal of pain, suffering, and mental anguish so you in advance try to persuade…

Prepping to Defensively "HARDENING YOUR HEART".