Havoc,
I normally do at least the half every year for the dallas white rock marathon. I haven't stopped but its too early to start training for december yet, so I've just been running 3-4 times during the week with the longest run about 5 miles. I tried to run the full two years ago and got hurt in training. My next goal is to train for the full this year. Maybe do San Antonio in Nov.
I only thought I was a runner until I read Dean Karnazes book, Ultramarathon Man. That dude is not a runner. He's a freak.
I try to do core workouts because it helps you keep good form when you run. I don't go to the gym as much as I should though and thats probably the reason I got hurt when I started doing my longer runs.