The Four Biggest Myths About Your Health:

A lot of people think the placebo effect isn't a big deal, because it doesn't ACTUALLY make you better it just makes you THINK you're better. But in reality, placebos are surprisingly effective for people with Parkinson's, depression, intestinal issues, and a variety of other things. And up to one-third of people who are in pain feel better after taking a placebo, because when your brain thinks you're taking a pain reliever, your body automatically releases compounds called opioids, which are kind of like morphine. Here are four more big misconceptions that most people have about their health.

Myth #1.) "Overweight" Equals "Unhealthy." In one study, more than 25,000 men were tracked for over 23 years, and researchers kept tabs on their health. In the end, men who were overweight or obese, but exercised regularly, tended to live longer than men who were thin but DIDN'T exercise. In general, doctors worry more about your body mass index, which is supposed to be below 25. But if you have a lot of muscle, it can be much higher.

Myth #2.) If You Have Bad Genes, You're Destined to Die Early. Scientists keep finding new things in our DNA, like the breast cancer gene, which significantly increases your chances of developing breast cancer at some point in your life. 60 to 80 percent of women who have the gene will develop breast cancer compared to 13 percent of women who don't. But it's not the same with other diseases, and if someone in your family died early, it doesn't necessarily mean you will too. In fact, scientists think the majority of cancers are caused by things you can avoid, like smoking, sun exposure, and a poor diet. And if there was a pie chart showing all the things that affect how long you live, your genes would only take up about one-third of it. The other two-thirds are things you can control.

Myth #3.) Prescription Drugs Are Guaranteed to Be Safe. People think that if the FDA approves a new drug, it means it's been thoroughly tested for side effects. But about 10 percent of the drugs that are approved by the FDA are later discovered to have MAJOR side effects that didn't show up in clinical trials. That's why you should stick with a medication if it's working for you, and not switch to some new drug just because you saw an ad for it on TV.

Myth #4.) Hospitals Are Sterile. The reality is, hospitals . . . and doctors . . . are often covered in nasty drug-resistant germs that could make you sicker or even kill you. According to the CDC, each year 1.7 million people in the U.S. develop infections while staying at the hospital, or immediately after they're discharged. And almost 100,000 of them die.