A major theme of the High Holiday season is the role of the י״ג מידות, or the thirteen attributes of Hashem. We were introduced to these attributes when Moshe Rabbeinu prayed for forgiveness for the sin of the golden calf.
Hashem Himself taught Moshe the י״ג מידות and explained to him that its recitation changed the heavenly decree of pure judgement into mercy. It was almost as if by saying these "magic words", the results would be favorable for the person saying them. This is especially important when we consider that Rosh Hashana is known as the יום הדין.
The Rabbis teach us that nobody can survive when we are faced with Hashem's דין, or justice. Therefore, we must judge others favorably so that He will treat us in similar fashion.
We should pay attention to these י״ג מידות and say them with great Kavana. The Selichot prayers have them several times as does the Yom Kippur prayers. And in the final prayers of נעילה, they are said at least seven times. May we all be granted Hashem's abundant mercy.