This is all very good advice (except for the "no rest" theory. that's just asking for an injury/death). l'll throw in what i (used to) do.
(I say "used to" because now i referee 10 matches per week and no longer jog because...well...i jog enough during the games)
I tend to prepare specifically for the referee fitness exams. So i jog quickly for 12 minutes, hoping to cover at least 2km (1.2 miles roughly). If i'm feeling kinda sore, i'll move this run into the gym on a treadmill or elliptical machine (it's easier on a machine).
Then i do short (50m) sprints, maybe 4 or so.
Then i do long (200m) sprints (run the longth of the pitch, immediately turn around and run back), at least 2.
This all takes about 15-20 minutes. Anything else i do is just a bonus (weights training, shooting, extra jogging, etc). I do that 15-20 minute training session every day, and usually some extra stuff about 3 times per week.
I know it's not really anything hardcore, but 1) i do it every day, so it's not meant to be strenuous, 2) you can always do bonus activities, as long as you do the minimum, and 3) it's better than sitting on the couch eating MacDonalds.
Somewhere through all of this, DO NOT forget to do your sit-ups! It's makes every other excercise so much easier if you keep up with your sit-ups/crunches!
With the 10 matches per week now, i skip the jogging and only do the sprints. I do the sprints three times per week, on matchdays. On non-matchdays, if i'm feeling up for it, i'll go and do weights training.
-Chas