A high-school teacher told all of her students to bring a clear plastic bag and a sack of potatoes to school for a project.
The next day, students were told to think about the people in their life who they they were angry at; all of the people who they refuse to forgive for whatever the person may have done. For each person thought of they chose a potato and wrote on it the name of the person they were angry at and the date their anger with them began.
They put the named and dated potatoes it in the plastic bag. Some of their bags were quite heavy.
Students were told to carry this bag with them everywhere for one week, putting it beside their bed at night, on the car seat when driving, next to their desk at work, etc. By lugging this bag around with it became clear how heavy and what a burden their anger was. They had to pay attention to it all the time so as not forget it and leave it somewhere.
Over the course of the week, the condition of the potatoes deteriorated to a nasty smelly slime. This made carrying the bag around very unpleasant. Pretty quickly, the students realized they wanted to get rid of the potatoes.
The lesson here is to recognize the price we pay for keeping our anger and negativity alive within us. Eventually it becomes very heavy and it stinks. We often think of forgiveness as something we give to the other person, but in reality, when we lighten our load by letting go of our anger, we realize that forgiveness is for ourselves!