Here's how my NikePlus logged my run. You can see exactly when I hit "the wall", and didn't think I could go any further, right at about mile 24. That's not a bad place to hit "your wall", but it didn't seem so at the time.

Those last two point two miles felt like a hundred miles. My feet felt like cinderblocks, and I was afraid to stop for fear that my body wouldn't let me get re-started again. But I plodded along to the finish line and weakly held my arms in the air. I had imagined myself crossing the finish line in a stronger fashion, but I'm grateful for just crossing at all. :)