Long Run DNF

DNF a training run ??
This is what I did today...
During the week, I was able to gather some of the best runners in HK for a solid long run on this Saturday.
S.: a real rising star... Recent winner of Phuket International HM (1h13 in the Thailand heat ... Impressive)
E.: a accomplished Ironman with terrific running
K: top Master in HK and unvaluable resource for the running community

Being a solo runner 99.9% of the runs, I was pretty excited on the perspective of running in such a group...
Well, basically "my legs did not show up"

Maybe was due to the fast workout yesterday, coupled with a 6 hours drive during the day, maybe was the heat of the first real day of Summer (at 7am, 29C + 80%rh), but I struggled from the start, my HR was abnormally high, I was completely lacking energies and it was going worse and worse at every mile...
After 14km I simply bailed out and walked 2km back home....
Got headache until lunch...
Hopefully just a bad day
The boys went on and scored 27km as planned (I guess they lost 5lbs at least)