Sri Chinmoy: Each person has his own description of the wall. What does hitting the wall mean? It means that your exhaustion has touched its ultimate height. You are totally exhausted. You have come to realise that if you run a few more steps, or even one more step, you will collapse. When you reach this point, everything may go blank before your eyes or you may see all black. You might feel that there is a thick wall right in front of you that you can't penetrate, or a vast ocean or a big mountain that will not allow you to go further. It is an obstacle that you cannot push aside, penetrate or go beyond.
If you have really hit the wall, then even with adamantine will you can run only one or two more miles. Hitting the wall is like feeling that all your life-energy has deserted you. It means that you have an absolutely real sense of collapse. Your body gives you the feeling that death is imminent. At that time, real discouragement — physical, vital and mental — assails your life. When you really hit the wall, all your strength and determination desert you.