disappointing 8

Today's run was difficult and disappointing. I was planning for a long run, though planned for it to be less than 20km - expecting in the 17-18km range. From the first step I knew that wouldn't happen, so I cut my expectations down to around 12km and mentally adjusted my route for a shorter run. I was struggling so much, basically just shuffling through it, that I cut it at 8, and 8km was after I forced myself to continue just a bit more. Besides for feeling tired and heavy, I was running hard (at least I thought I was, during the first couple of kilometers) and still going at a crazy slow pace...