Psyching up for the long run..

Never forget that racing - especially at marathon length - is uncomfortable. You can't improve without sometimes venturing into discomfort. But these occasional ventures must be separated by returns to your comfort zone.

Aim to run at least two-thirds of the marathon distance before raceday. View your long run as a fulldress rehearsal. Test the shoes and clothing you'll wear on actual day, and the food and drinks you'll take, and the intervals at which you'll take them.

Take your long runs as much as one minute per mile slower han projected marathon pace. At faster paces, these runs become too much like the marathon itself - and require long recovery periods that interrupt regular training.
If possible, extend your longest training run to marathon length. Try to train as much time as you expect the marathon to take, even while going less than 42.195km becuase of the slower training pace; in other words, get used to lasting the full time of the race.

Simulate the marathon distance in long runs, but at a slower pace. Mimic racing pace in your fast runs, but only at shorter distance; Combine full distance at full pace only when it counts - in the race itself.