I was never a runner until I started c25k. I always tried but could never discipline myself enough to run longer than a minute or two. SO I was so excited when I ran 20 minutes straight during the training. It gets harder after that point but once you finish the training, you develop a passion for it and you can just keep going.
My advice is to keep your pace as slow as you need it to be. My jog was incredibly slow, but I was still jogging and keeping my breathing even. That's the key. Once you've lost your breath, you're done. Speed comes later.