6 Mar - not really up for it today - it's going to be a hard week

I was feeling surprisingly good yesterday on my rest day, considering at the end of Milton Keynes I felt the worst ever, I can remember feeling after a run.  But one night shift later, things have changed.  By the time I got out it was already dark and as I set off I knew it was going to be difficult.  I seem to have managed the short intervals up til now, but can't seem to carry off the pace for longer distances and I find it difficult to get any enthusiasm up when it's dark outside.  Of the so called 'fast' 1.5 mile intervals, the first was brisk to steady and the other 2 were steady to slow.  Very disheartening to hear the Garmin constantly beeping away at me to tell me I'm running too slow and I can see the target of 4 hours around London slipping away and looking more like 4:15 if I'm lucky.