By conscious breathing you can learn how to get control over your hormonal system and release happy hormones on will.
There is no such thing as an autonomous nervous system. Our cortex (thinking brain) can influence all systems in our body. Including the "autonomous" system which release hormones. Happy, sad, DMT, adrenaline. You name it.
Wim Hof is teaching you how to do this. You can start by watching this documentary:
RE: Why are humans never satisfied?