: Training in varied conditions—hot, cold, or even wearing non-traditional gear like hiking boots—to ensure the body can perform anywhere. 2. Biological Survival

: Building a "combat-ready core" through functional movements like single-arm farmer's walks and barbell rollouts.

: Using a "hybrid endurance" approach, such as combining running with rucking (walking with a weighted pack) to increase durability without the high impact of endless miles.

: The Washington Post notes that viruses like SARS-CoV-2 are "hard to kill" because they aren't technically alive; they are simply genetic material waiting for a host, making them resilient to many traditional environmental threats.