These chemicals speed up your heart-rate, shut down your immune system, digestion, and reproductive systems, allowing you to use all the energy that would usually go toward, say, digesting a granola bar for swimming like hell to the beach.

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"You are the guy who decided in 30 seconds to go up and spring a woman from a house of hell that she's been in and was desperate to get out that door with her 6-year-old daughter, " Walsh recalled saying.

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