Here's a question: How do you know what you know about the basic rules of good health?

If two minutes pass and you're still scratching your head, you probably have some gaps in your understanding of fitness, wellness, digestion and longevity. Perhaps you were in shop class. That's fine. But it's time to catch up.

On the bumpy road to a healthier, happier lifestyle, intellectual laziness takes you nowhere. You need to learn what you don't know, or you may get bounced out of the truck altogether, and in at least one state, shot from above by a moving plane.

Repeat after me: Self-care is the best care. Completely surrendering to our current, disintegrating, U.S. medical system can be a risky business. Their business, our risk. Doctors have no incentives to prevent problems, only to treat them. Drug companies hide bad results. Hospitals spread infection.

It's a stress-filled jungle out there, all the more complicated by confusing insurance rules, endless medical forms and robotic rejections of legitimate claims.

When it comes to living a stronger, safer, saner life, all parties can agree: smart self-care, anchored in a true understanding of our bodies and how they best function, goes a long way toward winning the war. As your most personal trainer, let me ask: Have you read or listened to a good personal health book lately?

One to consider is "Medical Myths That Can Kill You and the 101 Truths That Will Save, Extend and Improve Your Life" (Crown Publishers, New York), by Nancy Snyderman, M.D., NBC's chief medical editor.

It's not a perfect resource — I think she'll regret downplaying damage done by cell phone use, for example — but on the plus side, it's filled with useful scientific facts and personal stories. Many of her science-based truths may actually startle you. Tap water is as good as bottled water. It's better to be fit than thin. Sports drinks can cause irreversible damage to teeth.

If you believe otherwise, Dr. Snyderman opines, it's because you have bought into a medical myth. (Because myth-taken sounds so much like mistaken?)

"[Medical] Myths are like smoke screens," says Dr. Snyderman, available online at www.Bewell.com. "Mistaken beliefs can be deadly. Two of our greatest enemies in the battle against life-threatening diseases are ignorance and the personal beliefs we bring into the doctor's office."

Here are a few of the myth-busting medical truths Dr. Snyderman reveals:

— You don't need to drink eight glasses of water a day.

— Thin people die of heart attacks every day.

— Earwax may predict breast cancer risk.

— Doing good deeds does a body good.

— Soft drinks may be linked to heart disease and diabetes.

— Eating chocolate does not cause acne.

— You can't catch a cold from being in cold weather.

— The worst room in your house to stockpile your medicines is the bathroom.

Whoa! That truth alone could sink the medicine cabinet business in a day. Medicine cabinets are good for storing band-aids and toothpaste, not medicines you take by mouth, says Dr. Snyderman. Do what she does and store yours elsewhere. The changes in temperature and humidity in your bathroom, she notes, can compromise the healing nature of the meds. (If they had any to begin with. — M.P. notes)

More news you can use:

— It's OK to use plain soap and water to kill disease-causing germs. They've proven to work just as well as antibacterial soaps.

— There is an association of doctors who make house calls! It's called the American Academy of Home Care Physicians (www.aahcp.org), and I'm bookmarking it.

— Got high blood pressure? If you're overweight, modest weight loss — only 5 percent of your body weight! — may be enough to bring your blood pressure down to normal. Normal, as in No Costly Drugs Necessary.

— A good laugh is good for your heart, Dr.Snyderman states. She quotes other medical experts as saying, "laughing 100 times a day gives the same cardio results as working out for 20 minutes."

OK, I'm a big believer in laughing, too, but this last bit can't be taken seriously. As I said, it's not a perfect book. As in another of the so-called Truths, p. 155: "Stress does not cause cancer."

ENERGY EXPRESS-O! DON'T MYTH THIS TRUTH

"There is no secret to a long, healthy life. If there is, it's the secret of moderation ... " — said by many, including Dr. Nancy "Herbal Love Potions Are Bogus" Snyderman

Marilynn Preston — fitness expert, personal trainer and speaker on healthy lifestyle issues — is the creator of Energy Express, the longest-running syndicated fitness column in the country. She welcomes reader questions, which can be sent to MyEnergyExpress@aol.com. To find out more about Preston and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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