At some point in every ultra race it gets hard. Really hard.
At this point you need to decide if you are going to quit or if you are going to keep moving.
How do you get through this point?
Dead easy, just ask yourself, do you really want to stop? Can you justify stopping to those waiting for you at the finish?
Are you taking the easy way out?
Are you dead yet?
No? then how much worse can it get?
Are you willing to suffer just a little bit more?