This is partly why I'm hesitant to say outright what forgiveness "is" and instead chose to focus on what happens in people when they cling to the resentment within and allow it to colour their interpretations of events, people, etc.
Forgiveness, as a concept, is so subjective that people can interpret it all sorts of ways. Here, it was more important to me to focus on what happens beneath the concept and interpretations of it, to get at the anger and resentment which leads people to become bitter.
It's also not that I want people to think in terms of forgiveness either. Perhaps it's too much of a "positive" word/concept to apply to the people they resent, which is fair enough.
Instead, I want to shed some light on the practical and psychological aspects of people overcoming their own anger towards others, and knowing when it's time to let any negativity fall into place if only to liberate themselves from being driven by it.