Why would meditation or simply taking deep breaths be considered a "spiritual" exercise? Perhaps because they are so deeply relaxing, both physically and mentally. And emotionally. And if you think of how "shut down" you get when you're upset, I think you can see this as a kind of sliding scale of awareness and openness. The more upset you are (anger, anxiety, or depression), the more narrow your focus, the more your brain and body get "tunnel vision" and fixed on survival.
On the other hand, if you become more relaxed, you become more open and aware. Your tunnel vision opens and expands. Your consciousness is free to explore instead of being fixated by some survival issue. You can become aware of your feelings, your surroundings, the feelings of others, and perhaps even the interconnected oneness of all things.
What wise people have discovered over and over again throughout the ages is that what your brain and body consider a "survival issue" is more often than not an illusion. Your survival is not really at stake. Learn to relax your bodymind and you see things differently. Remove the stress hormones from your system and you see things differently, and you react to things differently, which elicits a different response from the world.
Adam Khan is the author of Principles For Personal Growth, Slotralogy, Antivirus For Your Mind, and co-author with Klassy Evans of How to Change the Way You Look at Things (in Plain English). Follow his podcast, The Adam Bomb.