I'm glad some ones mentioned good shoes and gait and that beginners usually push too hard too fast,
But I'm surprised no one has mentioned that pain while exercising = bad!
Getting sweaty and out of breath and your muscles burning and twitching is fine, sharp, dull, achey, twingey pain is NOT GOOD and will cause permanent damage.
I'm overweight and at over 200 pounds aka just under 15 stone, I couldn't run.
My knees would die and it would not be beneficial. I'd be better swimming, walking, cycling or dancing in the beginning and really having an honest look at what I eat.
When I was about 11/12 stone, running was not as issue, I was running half marathons, my knees wouldn't hurt at all.
So depending on how heavy you are, I'd recommend saving the running when your knees are stronger and you are lighter?
Good luck and remember you're lapping everyone on the couch.