Most of the things that make us healthier and help us to live longer are within our control, says Dr. Nancy Snyderman. Dr. Snyderman talks to Gayle about her book Medical Myths That Can Kill You: And the 101 Truths That Will Save, Extend, and Improve Your Life.

In her book, Dr. Snyderman debunks some of our society's common health myths. She says too many people in today's world bypass doctors and self-diagnose instead, going online to type in their symptoms and telling themselves what is wrong instead of getting professional help. "When things go south, you have to be smart enough to know your body, to know information and to know how to access the healthcare system effectively," Dr. Snyderman says.

In addition to discussing health myths like the idea that annual check-ups are obsolete, Dr. Snyderman also provides "truths" in her book, such as "happiness is a state of health," which she says is one of the most important components of being healthy. "You have to love to get up in the morning; you have to love and surround yourself with the people that bring you value," she says. "Happiness is a really important commodity in life."