Distraction works because it interrupts your mood and forces you to “change gears”. Many negative moods contain an element of rumination to them. When you ruminate, you go over your problem or worry again and again in your mind.
Source: Self-Soothing Techniques: Distraction @ CenterSite.net: Connecting you to your community
image: Mindful Mallorca Labyrinth Walk, Es Trenc by DoSchu under Creative Commons license