I started running last year, and absolutely love it, you'll be suprised how quickly you get fit enough to go further and faster too.... good luck!

I run quite often but have a problem with my knees which can be aggravated by running, very frustrating. While sometimes I do just have to rest, I've found that good shoes help, as does getting plenty of Omega 3 in my diet. I also try to mix up my exercise a bit - try doing yoga, cycling or swimming (I do yoga and strength training, ie. lunges with weights etc)- anything with less impact that helps strengthen the muscles around your problem area to help support it.

Hope that helps!