Inspired by SkyRe's combat module.

Features:
Buffs and debuffs based on current stamina level:

Stamina  Effect
90-100%: 10% more melee weapon damage, 10% better blocking
 75-90%:  No effect
 60-75%:  6% less melee weapon damage, 4% slower bow draw speed
 45-60%:  13% less melee weapon damage, 9% slower bow draw speed
 30-45%:  21% less melee weapon damage, 15% slower bow draw speed
 15-30%:  30% less melee weapon damage, 22% slower bow draw speed
  0-15%:   40% less melee weapon damage, 30% slower bow draw speed

Crossbow reload speed is unaffected.

Stamina now regenerates at full speed, whether you’re in combat or not. (Was 65% less total regeneration in combat)

Installation:
Use your favourite mod manager or extract the file to your \Skyrim\Data\ folder.

If you want NPCs to be affected by this mod, you can use ASIS to make it so. Simply add "xLETHxPerk=1" to ASIS' NPCEnchantFix.ini and run the patcher.

Manual Uninstallation:
Delete these files:
\Skyrim\Data\Lethargy.esp
\Skyrim\Data\scripts\LethargyInitialisation.pex
\Skyrim\Data\scripts\source\LethargyInitialisation.psc