Basics
Endurance represents how long you can suffer the hardships of adventure before needing an extended period of rest. Your endurance will run out gradually while you are beyond the safety of your haven, due to hunger, thirst, exertion, and the compounding stress of constant danger. When it falls dangerously low, you will need to return to your haven to recover.
Your calling determines your endurance.
You start each new adventuring day with a number of recoveries equal to your current endurance. You can spend these recoveries throughout the day to regain vigor. If they run out, you'll need to rest to regain them.
When you finish a night's rest, you lose all unspent recoveries, then gain a number equal to current endurance. Day after day, as your endurance fades, you will find yourself with fewer recoveries to count on.
These are some of the common ways you might lose endurance while adventuring.
You must eat each time you take a moment's rest or a night's rest, making a supply check for a ration in your inventory. If you cannot, you lose 1 endurance.
At the end of each day, if you didn't take a night's rest at any point, you lose 1 endurance.
Failing a check and incurring the harmful shadow may cause you to lose 1 or more endurance.
When you take damage from an attack while dying, you lose 1 endurance.
You lose 2 endurance when you successfully retreat from an encounter.
Running out of endurance represents the combined effects of starvation, exhaustion, and injury. If your endurance falls to 0, it cannot fall any lower, and you no longer regain any vigor or recoveries from a night's rest or any other means.
You die when you take any damage while dying and you have 0 endurance.
The stress and fatigue of adventuring can only be undone by spending an extended period in relative comfort and safety. When you take a day's rest in your haven, you regain 3 endurance.