Basically, I ran until I felt like I was dying (maybe 30 sec at first) and then kept running for a few more seconds (10-30 seconds), and then walked until I was almost but not completely comfortable, then repeated.
This isn't all that different from very very mainstream recommendations (Glover, Galloway).
Start with a time block, usually 20 or 30 minutes. For the first week, you're going to walk the whole thing. No running allowed. Walk for exercise, not for a nice evening stroll. Starting the next week, you're going to walk for the first five minutes and the last five, no running allowed, but for the middle 20 minutes start running slowly; when you get tired, walk until you feel good again; repeat for the 20 minute block. Gradually your running time will increase and your walk breaks in between will decrease. Don't push yourself-- if it's not easy to keep running, you should be walking.
You've had your whole life to get into the shape you're in (or not in) now. You're not going to turn into a great distance runner overnight. And that's okay.
IMO C25K is way too more ambitious for most inactive people and the speed at which it increases activity will tend to lead to injury and/or dropouts.