“Exercising the stress response just allows a person to assert a measure of control when the environment gets challenging.” EnvironmentStressControlChallenge Book:What Doesn't Kill Us: How Freezing Water, Extreme Altitude, and Environmental Conditioning Will Renew Our Lost Evolutionary Strength Source: What Doesn't Kill Us: How Freezing Water, Extreme Altitude, and Environmental Conditioning Will Renew Our Lost Evolutionary Strength