In context, I am looking for a word that refers to something that is in our way and inevitable, a conundrum. The sentence runs "It was there where I survived the greatest obstacle we will ever know. It was there where I survived myself." Obstacle doesn't follow the flow of the rest of the literary style. I want to make the work personable, relatable, and inclusive. I've considered "enemy" and "darkness," but again I want something broad enough to relate to every perception. Just a single word that could convey to anyone that THING that we've all had to overcome. Everyone sweats, what makes them sweat?
(noun) a demanding or stimulating situation, career, object, etc
"Challenge" has slightly more positive connotations than "obstacle" these days.
In your example:
"It was there where I survived the greatest challenge we will ever know. It was there where I survived myself.