Stamina is used for almost all actions in darkfall. Stamina can be regained naturally through regeneration, or by eating food, drinking potions, spells, or resting. It is also possible to have the effects of resting and nourishment, and potions at the same time.
At 300 Stamina, you can buy and train the Persaverance Skill
At 350 Stamina and 100 Sprint you aquire the Fleet skill?