Tried a faster run the other day W7 R1 and managed it (upped my speed from 11min/km to 9min/km) and still managed to run for my 25 mins - it was probably about 3km.
Did a bit of extra walking (afterwards) so that I could get a 'feel' for the full 5k distance (that might happen one day).
I did discover that I am now certain that when it happens I WILL be able to run for 30 minutes, but if there is any sort of gradient (upwards) on the last section that might well be a big challenge!
But... perhaps as Sarah said last week, I'm now a "runner" as I seem to be able to 'keep going' regardless of my body screaming at me to stop.
(I have to admit, I don't think I could keep going for 50+ mins running at this stage if I was to 'run' a full 5k even at my slow pace - but that is for work postgraduation methinks).
PB....
(W7 R2... later today, hope my Achilles exercises have worked)