What are the things that need to be said prior to "forgive yourself !" in order to make it possible to understand what "forgive yourself !" means?

What are the things that need to be said prior to "forgive yourself !" in order to make it possible to understand what "forgive yourself !" means?
What are the things that need to be said prior to "forgive yourself !" in order to make it possible to understand the value of forgiving yourself?
What are the things that need to be said prior to "forgive them !" in order to make it possible to understand the value of forgiving them?