In this mastering, no one can own you as you own yourself. You are not a slave to your sensory desires nor are you a slave to your lower ego that like a little two year old, wants to wreak havoc on all that is. Just take a look at what is going on around the Earth: much chaos due to humanity not being in control of its mentality and physicality. It is running amok.
The way to practice this mental and physical mastering is to start small by eating more healthfully, controlling your emotions more often, balancing your way of life by not doing or taking in too much of one thing. Live more in moderation. Don't over eat, stop obsessing, stop blaming, stop hating, stop judging especially yourself. To master your emotions, begin to live in loving detachment. Smile more, laugh more. Stop being taken in by so much us vs. them. Change up what you do habitually.
This is not a cavalier thing, this is a must do, not only to become Spiritually aware and free but to ensure your happiness. Right now you are a slave to your ego, a slave to your stomach, a slave to your job, a slave to your cell phone, a slave to your TV. These things own you. Is that how you really want to live?
Being mindless is not the road to evolution but the road to devolution.
Discover your freedom in your mastery of self. I assure you it's the path to your greater fulfillment as I have done this and I live pretty much stress free. I live with a Zen like tranquility. Please don't get me wrong as I am still acted upon by Cosmic and Earthly forces but I now choose how to work with them for my benefit not my detriment.