If you want to improve your fitness beyond just walking and you can't run yet, one suggestion is you could walk on a treadmill set to an incline. I was doing workouts like this during my recovery from a stress fracture, when I couldn't run due to the impact on my foot. Set to 3 or 3.5mph and then raise the incline to 5% or so and you'll get a really good workout without having to subject your body to the impact of running.My doctor says he would prefer that I not start running until I hit 300 lbs. I've set that as my goal for my birthday, April 16th ... at which point I will begin the C25K program. That will then give me another 4 months to prep for the Hartford half-marathon. I will sign up for that event.
In the interim, I will continue my walking program. I'm doing at least 6 miles a week right now (2+ miles, 3 days a week). Any suggestions that you all want to throw my way will be greatly appreciated.