Run until it hurts is so ambiguous. What if they fell down after two steps and banged their elbow pretty good on the ground. That hurts. Done? Stubbed toe on fifth stride. Hurts. Done? Player is a huge pussy. Running any amount always hurts at all times. Done? Total nonpussy and in great cardiovascular shape. Run for hours? Dumb.
Also, hurts? What the eff does that even mean? I'm not sure about this.