Master the art of breathing serenely. Since you are continuously breathing the entire day, this is the most powerful and effective tool for creating the peaceful feelings that are conducive for patience.
As soon as you begin to feel impatient, let the feelings you experience be the start of your focusing on the gift of oxygen. As you exhale, feel all stress and tension leaving. As you inhale, feel the fresh oxygen traveling from head to toe relaxing every muscle and every cell in your entire body.
As you breathe, repeat the word, "Patience." Say it with gentle and soothing patience. As your brain is conditioned to associate slow breathing with patience, the very act of breathing slowly will continuously enable you to be more patient.
(from Rabbi Pliskin's book "Patience," published by ArtScroll - www.artscroll.com)