I know a few peeps who are preparing for a marathon and thought I'd share a favorite workout.
Hop on the track of course...
Warm up with a mile or two (well, I guess you can do this off the track..and better so).
Run 800m at goal time (in minutes). If your goal is to run a 4 hour marathon, your 800 pace should be 4 minutes. If you want to run a 3:15 hour marathon, your 800 should be 3:15 minutes.
Recover between 800's with a 400m jog.
Repeat 8 times*
Cool down with a mile
*you'll thank me later