In this Unity tutorial I show you how to make a stamina bar that can recharge, be drained, and have discrete amounts taken from it. A stamina bar is quite similar to a health bar, with the main difference being that you probably want a drain ability with it. The process of coding it up is pretty easy, but if you have any issues I'm willing to help in the comments. :)
White pixel/square link - https://i.imgur.com/hJ1YgsW.png