It’s obvious that good health is much more than how you feel.  It is your ability to handle physical, chemical and emotional stress.  We are built with many mechanisms that allow us to adapt to these daily stressors such as shivering when cold or your immune system kicking in when bacteria enters your body.  So many forms of stress  threatens your balance: heat, cold, wind and rain; bacteria, viri, pollen, mold, fungi in the air; cancer cells with their deranged genetic instructions that constantly arise within; pollution and chemicals; cuts, bumps and bruises; school, work, marriage, babies, bills, a mortgage – and you must adapt to them all.  
If you didn’t… a hot summer day would boil your brain, a winter night would freeze you solid; every inhalation would bring massive infection, tumors would overwhelm you, and a cut would drain all your blood. Without adaptation, your heart would continue pounding after a workout; alcohol and other drugs would never break down, you’d stay intoxicated for life; be adrenaline high, or a moment’s anxiety would last a lifetime.
Thankfully, you usually adapt to life’s stresses because many mechanisms are built into you for this purpose.  They are as dramatic as an adrenaline rush when confronting danger, or as ungraceful as gagging. They all say the same thing: Survive! Survive changes in the weather; survive bacterial invasion; survive pollution; survive emotional heartbreak; survive excitement; survive work; survive in the big city—and thrive!