Stamina

Your Chief's Stamina is represented by the blue bar at the bottom of the screen above your Health bar.

Your total stamina can be increased by Skills, your Chief's chosen Name or warpaints.

Both Running and Dodging/Rolling will decrease your stamina.

Riding a horse, even with shift pressed, will not drain your stamina and a horse doesn't have any stamina. (it does have health)

There are many Consumables that can replenish your stamina or even increase your max stamina temporarily.