Keep at it! I am a runner also, when I found out I asked my doctor if it's safe to continue, he said if you have been doing it before it's perfectly fine to keep running. It will also help lower your risk for gestational diabetes and preeclampsia.
Talk with your doctor, if you have been running it's usually safe to continue to do so since your body is used to it. My neighbor continued to run up to 20 miles a week until her 35th week, but she was running 40 miles a week before she got pregnant so it wasn't the same kind of stress on her body that it would have been for lazy me. :-) Even if you don't run now, you should be okay to run/jog some even into your third trimester so long as you ease into it and don't go crazy. Bottom line, again I would talk to your doctor about your specific situation and see what they recommend.
I think it's ok in your first trimester but after that I would walk. I walk a mile a day good luck and congratulations