I did it.
On 1 July I went shopping for some shorts and a shirt and a comfy pair of trainers and then a couple of days later went for my first "run" which involved intervals of 1 minute running and 90 seconds walking repeated 10 times. Over the next 25 runs (every other day with a few two-day rest breaks) I first inched up the amount of running vs walking and then stretched the total running time until today I'm running 30 minutes comfortably (ok, the dripping with sweat and desperately wanting to stop kind of comfortably). Today I gave myself an extra push by running with a metronome for the first time - 150 bpm meant I stuck pretty close to 12 minutes per mile, and I didn't die, which gives me hope for a sub-30 minute 5k somewhere in my future.
I'm amazed. I imagined I'd get stuck somewhere in the middle and not be able to move on and then give up disillusioned and ready to spend the winter back on the couch. Instead, I'm loving looking over my stats while my coffee brews and ready to have a go at my first timed 5k on Saturday.
I've become one of those people.