As for the running, great job!!! It's so much easier to be proactive about your weight than to try and lose 50 or 100 lbs later.
For stamina, it's okay to do 3 minutes of jogging followed by 1 min of walking. Just work up on the ratio so eventually you're doing 10 min of jogging and 1 min of walking and then no walking. Then slowly work on increasing your distance. Give yourself at least one or two rest days a week, and one or two days of cross training like weights or yoga. It'll take time to work up to longer distances, and once you get up to a few miles you'll want to work in some days where you focus on speed rather than distance.
Make sure you have good shoes and try and focus on your stride. You want to run with your hips over your toes, landing more on your toes, and pushing off from your toes. Running where you land on your heel and roll forward to push off on your toe means you land with your knee locked and jar your ankle/knee/hip and cause joint problems and shin splints. Google low-impact running if you want more info on that.
Most of all, be patient with yourself. It'll take time to get good at it and to see results. I don't know if you have other goals besides maintaining your weight, but I run a couple mornings a week before work, do weights or stability ball workouts a couple evenings after work, and go for a longer run on Saturday morning.
It's all about what you can make work for you though.
And remember, slow miles are better than no miles!
Michelle - Proud DR Rockette S: 28JUL07, D'd: 29OCT09 http://tinyurl.com/27j9qo2
