Yet another good reason to ride a bike (instead of driving). This article from the LA Times highlights the emotional (and physical) stress caused by congestion.
On my way in this morning, I got stuck behind a slow car. So I slowed down too, and took the opportunity to hum a song to myself and listen to the birds sing. I can hear a car behind me, also stuck behind the slow driver, revving her engine and getting frustrated. Slow car finally turns, and we're both free to go. Frustrated driver guns her engine and charges off. I keep humming.