While I followed my own version of C25K to get to running, I think there is a flaw in the program. I found, and still find, that is, 50% of the discomfort in running a mile is in the first quarter mile, which I don't think you get to for several weeks.
I'd go as far as to say that 50% of the discomfort in running 5K is in the first 1K. *Starting* a run - until you get your stride, heart rate, and breathing to the right place is the hard part. At least to me. You won't get the reward in C25K until you are three quarters of the way through it (the reward being that sweet spot where you're breathing free and your legs are just sort of spinning under you).
I'm working on push ups and sit ups and these 2 programs are now kicking my ass. Also, I'm not looking forward to tomorrow on week 4 of C25K program.