After giving myself time to recover, I switched to only dirt trails. Not only is dirt a much better cushion for each of your footfalls, but I found it so much more pleasant to run through the woods. (Though the "beware of mountain lion" signs did make me a little nervous.)
But it's not always possible to find a nice dirt trail when you're training. If you're planning on training for a half marathon, a full marathon, or some other long race, remember to consider if you're going to be traveling. I found scheduling time to train most difficult when I was traveling, mostly because it took so long to find a trail I could run without injury. Don't let this dissuade you, though. With the right marathon training schedule and the right guidance, you can run the race of your life.
I found the information from The Non-Runner's Marathon Trainer