Wow the distance you guys can run is huge. I've just started trying to get fitter, today is day 1 of not smoking, and have been going for 5km walk most mornings with the missus and bub, but this week start work at 7, so CBF with an hour walk in the morning. Instead I've been doing a shorter 2.5km one at a quicker pace, with some jogging thrown in, and can only go about 600m before I need to cut back to a quick walk for a couple of hundred meters, then make myself go again.
I know that'll pick up, especially with not smoking, but atm it's nothing compared to you guys. I've never been particularly fit, and most years at the start of summer I think of doing something about it, but this year with having a daughter I have motivation to really do something about it.