I remember having a week like this when I was doing C25k. I think it was around the 3rd or 4th week. I had a migraine, was working late, etc. You know, life gets in the way sometimes. That "all or nothing" mentality doesn't help anyone - that is a huge lesson I had to learn. I beat myself up for not running for a WEEK! Yes, an entire week! I remember trying to exercise at home, but feeling too lazy and too out of shape. At that point, too, running was still not fun for me. It was difficult and I hated pushing myself. I would have much rather gone home, opened a bag of chips and watched TV until bedtime. Yeah, I get how you're feeling.
But guess what? Changes don't happen that way. Is something small better than nothing? Absolutely! Oftentimes, I tell myself that I will run for one mile. If at the end of the mile I still want to give up and go home, then I can. But 12 minutes out of my life will not be the end of the world. More often than not, I will find myself pushing for a second mile, and maybe even a third.
Lastly, part of the reason I checked out of C25k halfway through is BECAUSE of the defeatist mentality if there was a day that I didn't run because of whatever reason. I'd get down and beat myself up for not sticking to schedule. This may not be the same for you, but allow yourself some flexibility. So you didn't run yesterday...so what? Do W2D1 today.
Don't get too burned out...listen to your body first.