It was my third attempt at this run today, having failed to complete it on holiday last week. I usually run on a treadmill during the week, with an outside run on a weekend, and so far I have completed all runs first time. I thought maybe the change of routine on holiday had caused me to lose momentum, although I did notice that my chest hurt while I run (I've never felt that before). Today was hellish - struggled to do 5 minutes, never mind 10. I feel so disappointed! I'm pretty convinced I might have some kind of lurgy, as my chest hurt again and I just could not get my breathing right, but I'm worried also that running on the treadmill has given me a false sense of security and that I'm not doing as well as I thought. Anyone had anything similar this week?