Eastern mystics and yogis for centuries have learned to consciously regulate things as "automatic" as their heartbeat, and meditation is a way of consciously altering brain function. So why do so many of us treat our bodies as inanimate objects - sacks of blood and bones, incapable of doing anything other than responding to stimuli unless told to do so by our almighty brains? If you stop and listen to your body once in a while, you might be surprised at what you might learn.
Obviously you know that your body can tell you things like when it's hungry, thirsty, or needs to sleep. But did you know it can also tell you what food is good and bad for it? How to relieve pain? What kind of exercise it needs? Actually it tells you these things all the time. We just don't notice, as most of us aren't trained to listen.