The user possesses limitless physical energy, stamina and vitality, is essentially untiring and can keep working, fighting, mowing, etc. at optimal efficiency under any circumstances and for an unlimited duration due to the fact that their stamina can precedingly regenerate.
Sakamaki Izayoi (Problem Children are Coming from Another World, Aren't They?)
Zombies (Quake Series)
Mummies (Quake: Dissolution of Eternity)
Ustanak (Resident Evil 6)
The Rowdyruff Boys (The Powerpuff Girls)
Alex Mercer (Prototype series)
James Heller (Prototype 2)
Minions of Set (Samurai Jack)
SCP-2317 - The Scarlet King (SCP Foundation)
Skeletons (Crypt of the NecroDancer)
Zombies (Crypt of the NecroDancer)
Sonic the Hedgehog (Sonic the Hedgehog)
BLU Pyrogun (TF2 Freak)
Bluster Blaster Sentries (TF2 Freak)
Bomb Bears (TF2 Freak)
Commander Bot (TF2 Freak)
Cremapyro (TF2 Freak)
CyborPyro (TF2 Freak)
Deed Goy (TF2 Freak)
Pyrogun (TF2 Freak)
Undead Stoner Scouts (TF2 Freak)
Negi Springfield (UQ Holder)
Saint of Killers (Vertigo Comics)
Kanade Tachibana (Angle Beats!) is a prime example of this power, she can participate in any fight against opponents while producing almost no fatigue toxins in her body.
Due to her infinite energy generator, Android 18 (Dragon Ball Series) can fight indefinitely without ever tiring or wearing down, allowing her to overpower and defeat Vegeta.
Majin Buu (Dragon Ball Series) has limitless stamina which, combined with his powerful renegeration, allows him to keep fighting at his peak indefinitely.
As long as his vengeance isn't fulfilled, Kratos (God of War) can perform limitless physical activities, relentlessly fighting colosssal opponents and entire armies without ever tiring.
Unlike the Powerpuff Girls, the Rowdyruff Boys' (The Powerpuff Girls) energy never wears down in battle. Instead, they continue fighting with no signs of needing rest.
Sakamaki Izayoi (Problem Children are Coming from Another World, Aren't They?) has exceptionally high power, because of this, as long as his opponent doesn't give up, he can continue to fight them with no signs of fatigue what so ever.
Due to their divine nature, The Minions of Set (Samurai Jack) possess a limitless amount of stamina and tireless bodies, allowing them to continue fighting and pursuing jack without the need for rest or sustenance.
Hercules (Marvel Comics) possesses virtually limitless stamina, allowing him to never get tire after any exertion