Wim Hof breathing technique can modulate immune response to pathogens (2014)
The paper mentions voluntary activation of the sympathetic nervous system and anecdotally from my own meditation and yoga practice I've found that I have some control over a very specific SNS response. I'm able to control piloerection ("goose bump" activation) any time I want, something I wasn't ever able to do before and found to be quite strange when I noticed myself gaining control over it.Not exactly an awesome super power, but I have found that it's helpful for cooling the body when I'm excessively hot during particularly strenuous yoga asana practice (back when practicing around other people in hot rooms was a thing).Note: In meditation practice piloerection is part of what is generally referred to as pīti.