A treadmill
From Create Your Own Story
After stripping you, the girls head you towards a treadmill in the corner. "It's our little test," Stephanie tells you. They start off by binding your hands behind your back, and your nipples to the handles of the machines, with some string and bulldog clips. They start you off on a nice gentle jog, as you run naked, your nipples hurting as the weight of the string and clips pulls slightly on them when you bounce.
The girls have some fun with you, making you run while pulling your knees up, while kicking yourself in the ass with each step, and by just making you run uphill and workout, sweating and breathing hard. "You're doing well," Anita tells you. "Now keep going," she orders, as she presses something into your ass. You think it's a butt plug, or something like it, and you keep on running, the plug making your already hot body hotter. Soon, the girls begin whipping you with a rolled-up towel on your feet, legs, ass, and pussy, although it seems only Cherise is accurate enough to be able to hit you there.
You continue through the punishment
You can't take it, and eventually slip off the treadmill
Requirements: This is a story about a young girl written in second person.