A long time since I last ran a marathon, but one trick that worked for me was to fool myself into thinking I was running a shorter distance.
So for an 18 mile run, I'd do a 2 mile 'warm up' at a very slow pace (say 11 min/miles), then 'run' a half-marathon distance (say 9:30 min/miles), and then 'warm down' for 3 miles (again, 11 min/miles). I'd keep telling myself I was only running 13 miles, the slow bits didn't count. It worked for me, didn't find myself hitting the wall in training at all. Might have just been the same affect as slowing down the run though
Just Run - glad to hear it was a better run, overtaking a boat is top work!
Had another session on the dreadmill today, made a lot easier by watching our boys and girls winning medals in the rowing whilst running - got to the end without really thinking about the run, which is great. Trying to crank up the training now to make the shorter runs all at tempo pace (7:45-8:00), kept this one nice and steady and came home in 39:40 for 5 miles, so 7:56 pace. Bang on. One of those every Friday will do nicely thank you very much.