The first and most obvious thing they have in common is breathing. In singing, learning how to breathe properly is essential for vocal technique. In yoga, breathing is used to relax, focus, and regulate one's physical and mental state.
When I first started taking singing lessons as a child, I would occasionally feel dizzy from taking in too much air. Because it's important not only to take in enough air, but also to be able to control it, even through long musical phrases and sustained notes.
Another common element is stress management. You might argue that yoga is a meditative and highly personal practice that promotes relaxation, while opera singers step onto the stage in front of an audience and often experience intense nerves. But if we look at it from a different perspective, psychologists sometimes recommend "letting it out"—expressing strong emotions through sound. Singing can serve a similar purpose. In opera and musical theatre, performers fully immerse themselves in the lives of their characters, which can lead to a sense of catharsis—emotional release and inner cleansing.
There is also the connection of working with the body. For a singer, the body is the instrument. Every vocalist understands that in order for the voice to perform at its best, physical strength, energy, and good health are essential. That means getting enough sleep, eating well, protecting the voice before important performances, and, whenever possible, avoiding unnecessary talking the day before a concert. During the colder months, many singers never leave home without a scarf and a thermos of a warm drink.
In yoga, the body is also viewed as an important instrument. Yoga teaches us to listen to our bodies, pay attention to their signals, avoid pushing ourselves to exhaustion, and strive for harmony with both ourselves and the world around us. Perhaps that is why many of the principles singers follow in caring for their voices and overall health are surprisingly close to the philosophy of yoga.
As we can see, singers and yoga practitioners have much more in common than it might seem at first glance.