Stress can be a contributing factor when it comes to health issues like high blood pressure, weight gain, hormone imbalance, anxiety, a weakened immune system and poor quality sleep just to name a few. It's not realistic to think we can eliminate sources of stress, but we can control the way we respond to stress, and choose healthy coping mechanisms like meditation, yoga, any type of movement you enjoy that elevates your heart rate/gets you breathless and breathing exercises.
If you're having a stressful day, and don't have the time for exercise or a yoga class, I encourage you to take a few minutes and practice one of my favourite breathing exercises: Box Breathing. Studies have shown that breathing exercises that slow the breath or have you taking deep breaths, like box breathing, reduce cortisol (stress hormone), slow the heart rate, reduce blood pressure, and stimulate the parasympathetic nervous system (specifically the vagus nerve - responsible for calming your nerves), which all work together to physically calm you down, and provide stress relief (1).
Dr. Mark George, a professor of psychiatry, radiology, and neuroscience says, "deep breathing is the best way to self-stimulate your vagus. When you take a deep inhalation, you stretch the fibers around your lungs. That sensory input travels up the vagus to your brain, triggers a deep exhalation out, which activates the parasympathetic nervous system and calms you down (3)."
Box breathing is easy, only takes a couple minutes, and you can do it anywhere - at your desk, in the car, the shower, or when you're in line at the grocery store. Find a comfortable place to sit, close your eyes (if you're not driving:), shoulder blades back and down, lengthen the spine and reach the crown of your head up towards the sky. Take a nice deep inhale through your nose for a count of 4 seconds. At the top of your inhale, hold your breath for 4 seconds, then exhale for 4 seconds or longer if possible. Repeat this 4 times.
In other words, take a deep breath and repeat.