Grievances are time based. They exist only in the past with what happened, or in the future with what you think will happen. In the present moment grievances do not exist. For a grievance that has already happened, when you bring this to the present moment, not only is the power and effect taken away from it, it no longer exists, because there is nothing to be remembered in the Now. This is how you heal large grievances that have had a traumatic effect on you. Think of them not as happening in the "past," but think of them as happening right now, in the present moment. In the present moment is where God is found and all healing occurs, instantaneously.