I learned this when I was a child. First it was a party trick cause I could give myself goosebumps on command. But as I got older it helped insulate me against an abusive parent, but also gave me the protection to allow myself to go deeper in relationships without feeling scared to get lost in it. The sovereignty of our emotions are a direct reflection of our nervous systems ability to self regulate. This practice helps you learn to anchor yourself so the storms - whether they come from other people or the world itself - don’t just sweep you away. You become the one who stays steady while everyone else spins. You learn to face the wave instead of letting it whip you around uncontrollably. And even if it does - you know how to heal from it, autonomously by returning to center at will.  Over time the capacity grows. The more you root, the more you can actually process without losing yourself in it.
It is not about becoming cold or superior. It is about becoming fluid, radiant, so everyone benefits from your sovereignty.
 
Simple daily practice. It builds over time. Once it resonates, it changes how you move through everything.
Good luck!