How we cite our quotes: (Part.Chapter.Paragraph)
Quote #1
God had placed him in a garden of infinite bounty, a Land of Goshen in which any man could prosper if only he had the courage and the fortitude to try. (1.1.20)
Although we'll be focusing on Hugh Glass for the bulk of this section, it's worth noting that he's not the only one with oodles of determination in The Revenant. William Ashley has plenty of persistence, too, the only difference being that his only goal is to make as much cash as possible.
Quote #2
They waited all morning for Hugh Glass to die. He never gained consciousness. [...] Still, his chest rose and fell, each breath stubbornly followed by another. (1.3.42)
Hugh Glass is so persistent that he doesn't stop swinging even when he's unconscious. That's boss status. What's more, this sets the tone for everything that follows, as it shows that Glass is far tougher than a human being has any right to be. Are we sure that this dude isn't a Terminator or something?
Quote #3
Glass sensed that his body was marshaling itself for another, decisive battle. Not at the surface, but deep within. (1.6.9)
As Glass's body slowly (emphasis on the slowly) recovers, we see him become increasingly focused on surviving this seemingly un-survivable ordeal. We wouldn't put money on it, but if anyone can do it, it's Glass.