I'm not sure how much Viking "requires" yet, but this is what he usually gets:
3x 15 minute walks on trails, 30+ minutes of playtime in the house (playing with me, games like tug or fetch etc), 10-30 minutes of training (includes walking around etc), and 2+ hours on a long lead wandering/running in the park. I don't do off leash dog parks but when nobody is around at my local park, since it's fenced in, I'll sometimes let him "off leash" for brief periods to run about. On some days we're doing dog sports (Flyball), other days puppy class (obedience), etc.
Viking gives me the impression that he can keep going for awhile. We spent 5-6 hours at a dog festival on Saturday walking around, meeting dogs, doing agility, going for a swim, and then running around at a local park that evening and he was still revved up to continue training. The only thing that really tires him out is mental exercise (dog sports, things where he has to really think about what he's doing, etc). I've slowly been upping his exercise over time and adding in more things.
Viking vom Zeder-Kamme (11/19/2011)