I've been doing the speedplay tattiefritter mentions. It has made a difference in my speed and keeps things interesting. My runs are all five miles or less, and I generally do it during the second half of the run, once I'm good and warm.
When I started running in April, I started on the Couch to 5K and I instantly resisted the plan (I don't like things that prescribed, though it's worked really well for other people). I just started with a mile route...I'd just jog as much as I could and walk when I needed to. Pretty soon I could jog the whole thing. Then I'd stretch the route a little farther, etc. I'm now up to 5 miles, running about three times a week. I never even planned to run that kind of distance...I know it's NOTHING compared to what a lot of other ladies here run, but I feel very satisfied running about 15 miles a week.
My DH ran cross country in college, and he said that once his buddies got him talked into joining the team, all his coach told the beginners to do during practices for the first month or so was "Go run a mile." They did do other work, but they weren't killing themselves on distance. So even most of those elite runners had to build up a base and start somewhere, slowly. I"m glad I eased into it, too...even as slowly as I added distance, my ankles/knees were really ornery this summer. Just now do things feel fine in the morning!
Try to take your time and enjoy it. It's really awesome to see the growth that eventually comes with the commitment!
2007 Trek 5000
2009 Jamis Coda
1972 Schwinn Suburban
"I rejoice every time I see a woman ride by on a bike. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood."
Susan B. Anthony, 1896