I completed C25K a liitle less than a year and a half ago at about 220lbs. I've never been a runner or athletic and now comfortably run 5km in about 30 mins. In fairness, I didn't finish C25K running at that pace. When I first finished, 5km took me over 50 mins. I could probably have walked it in the same amount of time or likely even faster but I felt proud that i could at least say I was a legitimate runner.
I don't do races. Partly because there are none around here but mostly because it's not my thing BUT what I do know is that C25K is an excellent programme that can help you reach your goals. I don't know what week you're currently on and whether you have the luxury of time on your side, but some weeks I repeated till I had them down. If you don't have the luxury of time to repeat the weeks, then if you feel you need to walk at any point, walk. Walk until you feel you can get running again. Some days are just not "good run days" for some reason. Push yourself but also know your limits and stop and walk if you need to. Oooh and also, run outside if you're training for a race. I only very rarely run outside and boy is it harder than running on the treadmill. If you must run on the treadmill a 1% incline makes it harder almost like running outside.
Don't worry, keep training and know that on race day, you'll be fine. Everyone I know who races says there's something about race day which makes you push yourself and go harder and faster than you ever thought you could. You can totally do this!!!
: Jan 2009: 275lb; 3FC Start Weight
: July 19, 2009: 257lb; Record Low Weight
: Oct 21, 2012: 152lb
Losing the Regain
Overall Weight Loss