The Health Pack is the player's lifeline throughout the game. Without health regeneration like in other first person shooters, the only resource of health replenishment are the scattered health packs found in the environment.
Health packs are normally more frequently found in enemy camps or outposts. The game's difficulty level controls the amount of health packs available to the player, higher levels provide less health packs. So the player should avoid being seen, engage in combat or venture into open areas. The ensure survival via stealth tactics it is recommended to constantly scope the environment with the Binoculars, sticking to thick vegetation, crouching/crawling and using strategic ghosting kills to progress.