Almost everyone has at least one “bad” long run/walk.
You may never be able to discover why, but if you know, learn! The tough ones teach you that you have hidden inner strengths, which you can draw upon in future challenges, both in training and in life itself. This will particularly help your confidence and your ability to withstand adversity in the race itself.
Where is the Wall?
Your wall is normally the length of your longest endurance session within the last two to three weeks, provided you are going at the pace you could on that day. Even a little too fast in the beginning will introduce you to the wall sooner. On a hot, humid day, you’ll bump into that wall before you should-if you don’t slow your pace down even more than normal from the beginning.
Even those who have missed a long one in the marathon schedule have been able to do the next long one by slowing down to at least three minutes per mile slower than they could run and by taking walk breaks much more frequently.
The more conservative you are, in pace, from the beginning, the more you can push your wall back farther and farther with little risk of fatigue or injury.