When I was in the Marine Corps, I would run 6 to 8 miles 4 days a week. I can honestly say I was in the best shape of my life. Running was just a part of the job and I got pretty good at it. However, after leaving the Marines in 1992, I stopped running. It was mainly the lack of structure that did it. In the Corps, you always ran when your platoon ran. In addition, every six months, you had to perform in a physical fitness test which involved a timed 3 mile run.
Now, after being out of the running world for 14 years, I am back at it again. I feel better. I sleep better. I look about the same. But the good news, is I feel better.
If you have the opportunity to run, even a mile at a time, do it. Running may be the cheapest sport you can every do. You get more excercise per minute than any other exercise. Finally, running is a great way to experience the outdoors.
Run, Forest Run!