It was "only" run/walk - in fact, very short run/walk intervals at a slow average pace of 8:30 mins per K - but I was shattered at the end of it. I think that I would actually enjoy this sort of distance - very pleasant coastal route - if it wasn't so "never ending". It is of course never ending because it is training for a HM - but IF I could/would run/walk for say 5K and have a sit down for 5 minutes : - before starting out all over again, I'm sure it wouldn't be so hard!! But we return to the fundamental question once again - why the H*** am I doing this????