So I was on track to do the above on Monday night, but a tightness in the back of my right leg had been niggling at me for a week. After a PT session on Saturday I decided to see a physio before running that evening (I had been all excited at the thought of the magic 20 minutes). I thought it was my hamstring, but it turns out it is my sciatic never that it tight. Told to rest until today.
I got up this morning with my mind and attitude in the right place, but for some reason my legs and body weren't. I couldn't really settle into it and had to walk for about 30 seconds about 10 mins in. I ran for another 5 minutes and then had to walk for another 1-2 minutes again. I managed to run the rest and added some time on at the end to make it up. But my body was just telling me today was not the day for an unbroken 20 mins.
Am I disappointed? Yes, i have been able to do all runs as the programme so far and I wasn't expecting any difference today.
Am I going to let it bother me? No, I shall have another crack on Friday. I know it is only a matter of time and I need to listen to my body. I think the cause was I didn't eat a proper dinner last night and I didn't really have any fuel in the tank to get through the run. Oh well, you live and learn.