The Athletic Complex was perfect for working out frustrations. That was why Derek frequented the building so often and he knew full well that he wasn't the only one who used it for those reasons. While some people accepted the prison fairly well, for others it came with a lot of frustration in a lot of different ways. Not to mention the way some people clashed with each other in here.
It was easy to read the frustration on this girl's face as she studied the buttons on the treadmill. He could tell there was just a hint of confusion there too, normal for someone working a new machine. He walked over to her in between work outs. "Might wanna stand on the side rails, pretty girl. Before you push too many buttons and the track starts movin' under you."