This one will be brief.
Fitness professionals over the last 8 years been increasingly moving their clients away from distance running because of all of the ill effects it can have on the body (ankle, knees & hips). They have been telling their clients to use interval training as a healthy alternative. While this is true, the simple fact that telling someone that running is bad just baffles my mind. Similar to static stretching, running has become the enemy of many. Well it's nonsense! I don't know about you but nothing feels worse than to go out for an occasional run, (of which I don't do much because of other factors), and feel like crap! Running for distance is a GOD made form of exercising that if used properly and in accordance with that persons personal make up and ability, can be a GREAT thing.
If you are able to run and do it effectively, then run. If you have issues as a result of running too much, then by all means find another way of getting in shape or staying in shape. I believe that we fitness folks prescribe a blanket approach far too many times when we should be advocating that people go out and run MORE. Running has never killed anyone last time I checked. If your a person who will only do long distance running and no other form of exercise, then you are misinformed and as a result will probably fall into the category of individual who will need to cease and desist. But if you, like to go for a nice long distance run as a means of adding it to all the other methods of training I do, then feel free to run until your hearts content. This goes for squatting, lunging, overhead pressing, doing abdominal exercises, using treadmills, bikes, ellipticals, and anything else fitness pros have told you are "bad" for you. Everything in moderation and with education.