Thanks so much @redcandlelight and @onedropbeat.
In answer to your question - I started c25k one January when I was the biggest I'd ever been, and frighteningly unfit. I was sick after the first run, and barely struggled through the first week. I remember being completely floored the first time I had to run 5 minutes in one go 
Anyway, I completed the course, with a lot of moaning and whinging along the way. But it felt good, and I carried on running. That May I did my first 10k and it wasn't pretty (I walked some sections and could barely move for days afterwards) but I got round in 65 mins.
It was around then that I caught the running bug and it became part of my life. I'd run 3x a week whatever the weather - and then 4x a week or even 5x if I had time. I upped the distances and the speed just sort of came with that. I then did my first half and first full marathon - again, not fast, but I got round.
After my first full marathon I joined a running club and that's when the effort started really paying off. Running with other people made it easier to push myself and gave me a lot more structure to my training (I'd never done hill sessions or speed sessions before, for example). I also got hooked on Parkrun and gradually went from being one of the slowest to one of the fastest there.
Since starting c25k I've gone from a size 12-14 to an 8-10. I don't drink any more, I eat better, and my mental health is much better - I used to really struggle with anxiety and depression, but running helps me get some space.
In terms of times, since finishing the course my 5k time has come down from 32 mins to 20 mins. I've run several marathons now, lots of halves, and have occasionally been first lady in local races - something I thought was completely impossible, when I was there lying on my garden path, heaving into the grass, after week 1 run 1 of c25k!! I never thought I'd consider 5k a "short" run and certainly never thought I'd comfortably run a half marathon before brekkie on an average Sunday. If I can do it, as a once-overweight asthmatic mum of two, honestly, anyone can. And remember, most women who are "winning" Parkrun in 20-odd minutes were once struggling to shuffle around the first week of c25k 