Stamina indicates how tired your character is. This goes down as you do various activities or move on certain terrain. Moving at higher speeds drains stamina faster.
(This table is incomplete)
|< 50%||Cannot run at 4th speed.|
|< 29%||Cannot dig.|
|< 25%||Cannot run at 3rd speed.|
|< 10%||Can only crawl.|
|< 5%||Cannot walk.|
Over time, your stamina will recover by taking points from the hunger bar. It can also be recovered by sitting on the chair (makes you hungry), drinking Tea (does not make hungry) or water (makes hungry).
Increasing your Constitution will reduce the drain to your stamina bar when using tools or swimming.