Did Aragorn have hit points? How much damage did Boromir take before he fell on Amon Hen? Did Gimli have to wait around to heal up after the battle at Helm's Deep? How much mana did Gandalf have, how much did using his powers drain him, and how long did it take him to recover from his exertions?

Most RPGs use fairly traditional means to indicate a character's status – health, hit points, vitality; mana, energy, spell points. Despite the different names given to these stats, the bones of the system remains the same: a character has a certain quantity of hit points to represent physical damage and spell points to power spell casts, with the occasional stamina or other stat thrown in for good measure. The max stat quantities are increased as the character gains experience. It's a tried and true way to let the player know how they're doing and help them manage their character's physical resources on the fly.