Word for surviving due to sheer will

Is there a word or term for this?

To survive due to sheer will; against all odds.

Example: The polar explorer survived because of sheer will. He could have given up and succumbed to the cold, but he forged on until he reached his destination, despite the grim odds.

Maybe tenacity? OED: “The quality of retaining what is held, physically or mentally; firmness of hold or attachment; firmness of purpose, persistence, obstinacy.”

I'm not certain after looking up the definition, but still, I propose:

persevere

to try to do or continue doing something in a determined way, despite having problems

https://dictionary.cambridge.org/dictionary/english/persevere

As in:

The polar explorer survived because of his fortitude.

fortitude TFD

mental and emotional strength in facing adversity, danger, or temptation courageously.

Endurance:

The ability to endure an unpleasant or difficult process or situation without giving way.

Note that, in the context of polar exploration, the story of The Endurance is a fascinating example of the concept.