I am not a runner. But I do walk on the tread mill for some cardio and to warm up. It was truly just walking for a long time, but in the last year or so I tried to put in little jogs now and then. It was never a target to run. Nevertheless, my 1/2 hour on the treadmill is now around 1.5 mins of running for every 2 mins of walking: hitting a new distance record (30 mins is all I can take) tonight.
I just gradually added more time on the run. At first, just over 20 seconds was all I could do, and then needed a 3 minute rest.
So; it's certainly not going to make me a marathoner, but I have a rhythm that I can maintain, and that feels good.