You can also throw in a couple fresh peppermint leaves if you want!
You can also use the back of a spoon to lightly press and rub the leaves. If you have a mortar and pestle, use the pestle to very lightly crush the leaves. Makes sure not to overdo it when you crush the leaves. The leaves should look crumpled and slightly greener, not mashed to bits.
It may seem like you are adding a lot of peppermint, but you are essentially making a strong infusion so that you can later add ice to the tea without diluting the flavor. You can also add 5 or so spearmint leaves, which gives the tea a slightly sharper flavor.
Make sure to either wait for the boiled tea to mostly cool, or use a pitcher that can handle hot beverages.