If the past two years has taught us anything, it’s that our well-being matters. As we head toward the end of 2021, more of us are taking proactive steps to stay well. At the same time, there’s a growing interest in optimization and performance. Across sports, fitness, education, and business, we’re looking for new ways to feel better and achieve our potential. But behind these positive wellness trends, the story is a challenging one. Stress is currently a leading cause of illness worldwide, contributing to between 75 percent and 90 percent of all human diseases. And we’re still battling COVID-19 and the anxiety caused by related political and economic considerations. As stress rises, a familiar adage springs to mind. We all need to “take a nice deep breath.” Or do we? As I explain in my book, “The Breathing Cure: Develop New Habits for a Healthier, Happier, and Longer Life,” …