Stamina is what you use for almost every action in Wurm. It is represented by a green bar at the [[HUD]] and never is higher than your [[Health]].
Some actions take up more stamina than others, but stamina is regained according to your [[water|thirst]] and [[food]] bars. If they are high, you regain stamina very quickly. If they are low, it takes more time.
It is said that your thirst bar has a higher influence on stamina regain rate.