Dean Ornish, MD has stated so clearly on his website:
"People often think that advances in medicine have to be a new drug, a new laser, or a surgical intervention to be powerful—something really high-tech and expensive. They often have a hard time believing that the simple choices that we make in our lives each day—what we eat, how we respond to stress, whether or not we smoke, how much we exercise and the quality of our relationships—can make such a powerful difference in our health, our well-being, and our survival, but they often do."
Part of my job is to repeat the wisdom of others. Gently.