I finally realized that the only person I've truly injured in these situations is myself. The person who cut me off probably went on to have a good day, blissfully unaware of my ire. In the end, my anger at them affects no one but me and those around me. This sort of anger, allowed to run rampant, has wreaked havoc in our society. It's the cause of much of the road rage violence we've seen around the United States.
People refuse to let go of their anger, and often it ends in injury and death.
But in Christ, we are new creations. But don't wrongly believe that we spring forth fully as new creations the moment we accept Jesus. No, we are constantly being renewed in Christ. We may never be perfect, but living a changed Christian life means we are ever striving to live by Jesus' example of perfect love. My anger didn't disappear the moment I accepted Christ as my savior.