Add a couple of Marine Corps (or Army, etc.) running cadences to your ipod. When you need to kick it up a notch during a walk or jog, turn on a cadence. This helps me stay on tempo, and if you turn up the volume, you can hear their footsteps keeping time. Makes me feel like I'm running with a team. Plus, most of the cadences are short, at 1-2 minutes, which works perfectly for me (a beginning runner).
You can get them on itunes, just look up "military cadence" or "Running to cadence with the US Marine Corps."