I Open a Gym at the End of the World

The apocalypse came and I inherited my family's gym that was going out of business. Others build shelters, stock up on cans, and recruit people with supernatural powers. I built a reinforced squat rack, stocked up on protein powder, and recruited... Members. While other shelters were fighting for a piece of bread, I was worrying about the body fat percentage of the members. When the tide of S-class monsters strikes, all shelters are crumbling. My members wore homemade barbell plate armor and carried battering rams made of gantry frames, blocking the front line. "President," they turned around and asked me, "can we use these monsters as weights today on leg training day?" I looked at the black crowd of beasts and nodded: "Okay, please be careful not to injure your waist."