Just wanted to say how great it is to finish a workout when you think there is no way you are going to dig yourself out of a hole. I am a marathon/ultramarthon runner and really have not given thought to speed workouts. However, I am training for a 10k/HM now and started doing interval sessions. I was doing a 6 by half mile with .25 jog recovery in between and thought I was done after 2 (turns out there was a good uphill on half mile 2). I kept going (thought I might as well push as long as I can) and the second I finished number 3 I knew I was halfway through and could finish the workout. Weird how once you are halfway through you can see the light at the end of the tunnel.
So, what are some of the hardest workouts you have done but somehow found the light at the end of the tunnel and were able to finish?