Typically used with: Endurance.
In short: tough it out. The Stamina skill is used when a character is performing strenuous activity. Many environmental effects require a Stamina check to shrug off, such as extreme heat, cold, thin air, or no air. Performing strenuous activity for longer than usual will also require one. Survivalists, backpackers, and free-divers would make heavy use of the Stamina skill.
Any time you're trying to push your body past its natural endurance limits will call for a Stamina check. In general, if you're trying to avoid moving down the Knockout Track, increased Stamina is your best defense.
You can make a Stamina check to survive in harsh climates like burning deserts, or arctic wastelands. The more extreme the climate, the higher the DL. If a character is suffering from environmental effects (e.g. heat, cold, aridity) and fails a check, he moves down one step on the Knockout Track. A new roll must be made each hour a character is in such harsh conditions.
Clothing and equipment meant to counter the effects of the environment, like heavy winter cloaks or airy white linen robes, grant a +4 to the Stamina check.
You need to make a Stamina check whenever you want to perform any physical activity for an extended period of time, for example hiking, running, laboring, climbing, or swimming. Once you pass the normal time limit, you make a Stamina check against a DL set by your GM. The DL should increase regularly as you keep going. If you fail the check, you can keep going, but you move one step down the Knockout Track.
For example, marching more than 8 hours will begin to induce exhaustion. Each hour past 8, a character will need to make a Stamina check at a DL of 15. This DL increases by one for every additional hour. Each failure moves you one step down the Knockout Track. The challenge is even more difficult if you're trying to jog with all your stuff. In this case, for double your walking speed, you can only go for 4 hours before a DL 18 Stamina check. Each each hour past that raises the DL by 2. You can read more about overland movement and its Knockout effects in Chapter 12: Adventures.
Holding Your Breath
In an environment with no air, a character who is not doing anything physically taxing can hold her breath one minute for each point of Endurance she possesses (thirty seconds per point if performing strenuous activity such as combat or swimming). After this, the character is considered to be suffocating. For each round spent suffocating, a Stamina roll against a DL of 15 must be made in order to keep from slipping one step down the Knockout Track. Each round the difficulty increases by one point (DL 16, DL 17, and so on). Once the character reaches step five (unconscious), if the airless conditions persist another round, the character suffocates. One skilled in Healing may be able to revive a drowned character if quick to action.