As a dog enthusiast, I would just like to second a couple of points people have been making:
1)8-12 months is a good age for a sporting dog to begin running "long" distance. Before then they are growing too fast and long runs may cause joint problems later on.
2) Before that time range, take your dogs on walks and maybe practicing jogging a mile or so with it. Dogs love to run and to keep it cooped up until it's a year old is not good for the dog.
3) Gradual training, just like a human, is the best way to go. Don't expect your dog to go on a ten miler right off the bat. Having said that, I've ran 15 miles with dogs who were off leash (meaning they were running about twice the distance as I was as they were exploring everything). The point being is that a lot of dogs, especially smaller hunting type dogs, are excellent runners and they absolutely love it.
4) Be very careful of heat. Heat exhaustion with a dog is a real concern. You'll be amazed how well a long-haired dog can run in the cold compared to the heat.
5) Be careful of bloat. A lot of sporting dogs are considered to be "deep chested" and feeding and gulping a lot of water, especially with older dogs, after exercise is something you need to try and prevent. As a general rule of thumb, don't feed your dog for two hours before exercising and wait at least an hour after exercising before feeding.
6) Make sure your dog is current on all shots. This is especially a concern with puppies. When you go to a park or even for a jog around the neighborhood, you have no idea if dogs that have been in the area are current on their shots. Some air-born virus, such as parvo, can be deadly.
7) Learn to walk and run with your dog comfortably on a leash. YOU need to be in control during the run because chances are you'll bump into other dogs along your route. The worst thing is to be completely helpless if confronted by another dog. Also, you don't want the dog to be dragging your around on your run; that just sucks. This will take a lot of practice and it's best to start training right away. Sporting dogs, especially those bred specifically to hunt (as opposed to show dogs), have a natural tendency to be out in front of you working, so this is something you'll have to work with.
Good luck and enjoy it!