None of us can fully protect ourselves from all the possible bad things that could befall us. That's just a sad fact of life. However, we can build personal firewalls to greatly reduce the risk of being hit by some things and delay others for as long as possible.
The risk of serious illness can often be diminished and death can often be delayed by building the firewall of good heath habits. This firewall consists of (but is certainly not limited to) eating right/getting proper nutrition; seeing your doctor and dentist regularly; getting recommended vaccinations (like the flu shot); having various checkups and diagnostic tests at recommended intervals; drinking plenty of water; getting enough sleep; avoiding excessive stress; abstaining from illicit drugs, smoking, and excessive alcohol use; managing your weight, sugars levels, blood pressure, and cholesterol; taking vitamins and supplements as recommended by your doctor; and exercising regularly.
Sometimes, no matter what people do or how they live, they are going to suffer serious illnesses and/or die at an early age. Others can do pretty much anything they want and still enjoy good health and a long life. In most cases, however, one's health and lifespan have a direct correlation to his or her lifestyle and personal choices. So why not build the firewall of good health habits to tilt the odds in your favor when it comes to protecting the most valuable thing you will ever have?