Although this workout seems somewhat "basic," don't let it fool you. If you're not in shape, you'll leave you last meal behind pretty quick...
Go to a local high school, junior college, or anyplace that has a quarter-mile (400-meter) track.
-jog 1 lap (one quarter mile) for an easy warm-up
-sprint "straightaways" (approx. 100 meters) as fast as possible (SPRINT MEANS SPRINT!)
-lightly jog "curves" (approx. 100 meters)
Repeat for 4-6 laps
-jog 1 lap for an easy cool-down
End with stretching.
(NOTE - one lap will result in two "sprints" and two "light jogs")