Starting my marathon programme

So, it was an 18,000m at marathon pace today. The C2 training guide suggests that marathon pace = 10,000m pace + (3 x difference between 5,000m pace and 10,000m pace). This suggests 2:05 for me which felt a little low. I think that my 10,000 time could be improved so based my projected time on that and went for 18,000m at 2:03. This was fine until I saw that my heart rate was creeping up above 158 - my higher "under threshold" value. I decided to keep under that heart rate and the overall split dipped to 2:03.4 by the end of the piece. I suspect that last night's wine did not help my performance!

I had worked out that with 1,500m warm up/down I would do a HM distance today and duly did this in a total elapsed time of about 1hour 30 minutes.

Metres today: 21,190