Not sure if you heard of 'the Ice Man' Wim Hof. He has this breathing technique that can help you get in control of your immune system and your endocrine system.(and over 20 world records broken, including climbing the Himalaya wearing just boots and shorts). He was considered the only one on the planet able to do this, an exception when tested in a lab. But he wanted to prove that everyone can do this, so he started training people his breathing method and when given the same test after the training all of his 'followers' were able to be in control of their immune/endocrine systems. I have been following the guy for quite some time now since his breathing helped me and I've still been doing it daily.
So yes we still have a lot to figure out about our bodies and our capabilities but I think we're on the right path.