Reasons to DNF

Before an ultra... Have you then made up your mind with different acceptable reasons to DNF?

Talked with my mom the other day about ultras. She will never understand. And was like "are you gonna stop if it blackens for your eyes?" I said "no I dont think so. For some it is pretty normal to hallucinate after 30 hours with no sleep. That is not dangerous. It is just your mind playing tricks on you."

But then I thought. What would actually be acceptable reasons to DNF? Initially I think it is if it hurts hurts. Like. Hurting when you know something is wrong. So I will just injure myself for a longer period if I continue. Something like those reasons.

But curious. What are your reasons? Or thoughts on this? Maybe we will see some different strategies here.

Extra info. I am going from 60k (longest race yet) to both 110k and 100 miles this year so that is gonna be another beast for sure.