Two weeks ago I had a slow tricky run, head and body just not up for it. Last Sat was the the best yet, then today was pants again. (We do run in the week too but not the full 5k - more like 4). What is it that makes it so? I could feel I was slower - only started to improve in last 2k - but chest and shoulders refused to let me go any faster! I tell myself at least I run but it's a bit discouraging. Got too used to constant improvements during program!