Why is it important to forgive yourself? Countless studies also show stress and anger can cause or worsen diseases, such as cancer, heart disease, and various autoimmune disorders. “When resentment is interfering with your life, it’s time to forgive yourself,” she says. “So many people have a constant, critical voice in their heads narrating their every move.” She says she calls her critical voice “Gertrude” and tries to counteract Gertrude’s eternal litany with positive affirmations — that she is getting better, that she is less angry. “Forgiving doesn’t mean not being angry with yourself, but not hating yourself.