Wall

Most people have heard of the "wall"... specifically hitting it.

I remember the first time I "hit the wall".  I woke up early for an 8 mile run.  By the time I got to my last 3/4 mile I couldn't run if I had to.  I could walk just fine, but my body just didn't want to run.

Fact is I left the house without food or water, and as I learned the hard way, that's not adequate preparation for a run over an hour long.  You wouldn't go for a long drive with an empty tank, just like you shouldn't go for a long run without adequate fuel.  Now I'll eat a banana, a yogurt or some fresh fruit before heading out.  I'll also take some water along with me, especially on hot days.