Why do humans struggle with endurance when worms thrive in toxic environments?

I was reading about how certain worms can survive in incredibly toxic environments, and it got me wondering why do we humans often find it so tough to build endurance in a clean, well-equipped gym? It seems like we have every advantage, yet pushing through a workout can feel like a huge challenge. What do you think is the key difference between our biology and theirs when it comes to adapting to stress? I’d love to hear your thoughts or any tips that have helped you improve your own stamina.