Running is great exercise. All you really need is a good pair of shoes (but please put on some clothes too), and it can be done pretty much anywhere. But, like anything else, there can be too much of a good thing.
If you love to run, or are just getting started, here are a few strategies you can employ so you can run for life.
1. Invest in a good pair of shoes. I see people trying to run in cheap shoes, getting shin splints, and giving up, or running in the same shoes for years. Running shoes break down eventually; replace them every 300 to 500 miles or so. Your feet and knees will thank you.
2. Try trail running. I abandoned the roads for the most part several years ago for softer terrain. It's easier on the joints, and it helps your balance. Bonus: there's usually a lot more to see out on the trail.
3. Cross train. Taking a break from running will work different muscles. Weight training will build strength, while running increases endurance. So go for a hike, bike, or whatever else you like.
4. Notice aches and pains. Your body is trying to tell you something. Don't try to run through pain; it will catch up to you eventually. If something hurts, it's time to slow down, take a break, or see a doctor or physical therapist. You may just need to do something simple like work on your flexibility, invest in foam roller or orthotics, or change your shoes. If it's serious, it's time to find out, so you can get back to running as soon as possible.
5. Give yourself a break. I used to run 6 days a week, and would feel inadequate if I didn't do a long run, had to stop on a steep hill, or ran slowly. When I had to take several months off because of knee surgery, I thought I wasn't a "real" runner. But you want to run for life, remember? That means it's OK to only run a couple days a week, to walk if you need to, or never run another race if it's not fun anymore. If you're out there running, you're a real runner!
As for me, I'll be out there on the trails, for life.