Exertion

You can knowingly push your body past its limits when the need is great and your will is strong. Characters can decide to power through any act of physical exertion longer than their body has any right to. Walking, jogging, sprinting, swimming, climbing, laboring, or even performing rituals. If you keep on doing whatever it is for too long, you fight Stamina Drain (and a whole bunch of lactic acid)..

Marching more than 8 hours causes Stamina Drain (DL 15; +1 every hour; tiring).

Jogging more than 4 hours (accounting for short rest periods and additional water intake) causes Stamina Drain (DL 18; +2 every hour; tiring). You'll be sore as hell the next day.

You can run at full speed for one minute. Continuing to sprint past this point causes Stamina Drain (DL 15; +1 every round; tiring).

Performing a ritual (see Chapter 15: Rituals) causes Stamina Drain (DL 10; +1 every hour; tiring).

If you're performing physical labor, the DL and frequency of increase varies depending on the job at hand.