I think I made a mistake (I know, another?). I ran a marathon Saturday (a week back) and gave myself a few days off before starting training again. I ran intervals on Wednesday and a long run yesterday. And after, I was seriously dragging. 

Now, the distances in either weren't high - 4x400 intervals at 1:45 and 11 miles @ about 10. I was running farther and faster prior to the marathon. So why am I dragging? I think I didn't leave enough time to recover from the marathon. Especially the intervals, but really both runs should have been slower. I'll run slower this week and let my body have the time it needs.