Obese, how to start running?

Question
Hello,

I am 30 years old and have gained over 100 pounds in the last 7 years, before that I was already 50-60 pounds overweight.  I am 5'11'' and weigh 309 (started this Jan at 330).  I plan to be 165-170 by August of 2007.  thats about 2 pounds a week.

I have a goal of being able to enlist as an officer in the Army Nurse Corps.  I would have to be able to do 42 or more sit ups, 15 or more push ups and run 2 miles in 21:42 or better to meet the army phys. requirements.

I plan to be able to do this.  BUT, right now, I can't run because my excess weight is a major danger to my knees and feet.  I have no problems walking for a long time.  

My question is at what point should I start jogging? (weight) and at what point would it be safe to start running?  I am willing to walk as much as possible to keep the weight loss up until my body is ready to condition it to run again.  At 16 I used to run a 7:38 min mile, after starting out at over 11 minutes, I trained constantly and that was my best time at seven 38.  I want to at least get my miles to 9 minutes, no more than 10 min a mile.

Thanks,

Carey

Answer
Hi Carey
First i want to say i admire you and wish you all the success.There is no precise time when you should start running.The most important thing carey is paying close attention and listen to your body.It will tell you when you can run or continue to walk.What i recomend is gradually working into a walk jog program giving the body time to adapt to the work load.Even if it is only 10 yards at a time,The body adapts quite rapidly if you give it time.To maximize the fat loss the longer your on your feet the faster it will happen.I would recomend a couple of times a week, work your way up to two and a half hours.You won't believe what that will do.Carey feel free to get in touch if you have any other questions.

To your continued success

John