Stamina

It is often debated whether Hit Points represent literal health or some heroic resilience and avoidance of damage. Stamina serves to remedy this by splitting the basic HP into 2 pools.

Stamina Points

Stamina Points represent a character’s energy and readiness. They’re reduced by damage just like Hit Points, but a character always loses their Stamina Points first, and loses Hit Points only if they’re out of Stamina Points. If a character takes damage exceeding their remaining Stamina Points, the excess damage reduces their Hit Points. However, they lose any temporary Hit Points before losing Stamina Points.

Class Hit Die	Class Stamina Points	Class Hit Points (1st Level)	Class Hit Points (Higher Levels)	Class
d6	2 + Con Modifier	4	2	Sorcerer, Wizard
d8	3 + Con Modifier	5	2	Bard, Cleric, Druid, Monk, Rogue, Warlock
d10	3 + Con Modifier	7	3	Fighter, Paladin, Ranger
d12	4 + Con Modifier	8	3	Barbarian

Variant: Rolling Over Fixed

You may prefer the variance of rolling for Hit Points as opposed to taking a fixed value. If you decide to roll for Hit Points and Stamina Points roll your classes hit die once. Your Hit Points increase by an amount equal to half the die roll rounded down and your Stamina Points increase by an amount equal to half the die roll rounded up + your Constitution modifier. For example if you roll a 5 on your hit die, your Hit Points will increase by 2 and your Stamina Points will increase by 3 + your Constitution modifier.

Restoring Stamina

Though Stamina Points and Hit Points function similarly when a character takes damage, a character recovers them differently. A healing spell, such as Cure Wounds, restores Hit Points. A character regains all their Stamina Points after a full night’s rest.
You can also take 10 minutes of uninterrupted rest and expend 1 hit die to recover all of your Stamina Points.

Bypassing Stamina

Some damage may bypass Stamina Points altogether. For example falling damage will always damage a characters Hit Points directly, regardless of how many Stamina Points they may have. As a GM you may decide that a source of damage ignores Stamina Points though this should typically be saved for rare and powerful sources or situations where heroic aptitude would not serve to mitigate damage.