Hitting a wall

One of my commitments this year is to run in a marathon(working on NYC) and a triathlon. So far I have not been doing much running and instead have been doing a total body training program...yoga, weight training, jump training, etc. Well, this week I'm getting back to the running as well. As I'm gearing up to get back to training for a run, I'm remembering when I trained for the 1/2 marathon about 5 months ago. When I first started training for it, the most I had run before that was 4 miles and I hadn't run in months. In the beginning three miles was a challenge, then as I continued to run, I continued to increase the distance I ran, working up to 13 miles the week before the half marathon.
As you run longer distances, something happens that long distance runners call "hitting a wall". This is what it sounds like! And the longer you run, the higher you set your goal, the more likely you are to hit it. I hit it at about mile 10. It basically felt like I was running uphill, on a treadmill going the opposite way and somebody filled my legs up with cement. A voice in my head said...time to quit...you never ran this far before....maybe your not ready. The reason I didn't stop was because the other voice that said, "but your felt like you were going to die when you ran 3 miles 3 months ago and now your running 10" was stronger. The higher we set any goal, the more likely we are to "hit a wall". All of those smaller goals that we set and surpass are all ammunition to get through that wall when it does shows up.