While we can learn or study techniques for almost anything we might want to accomplish, real understanding is not the mere accumulation of knowledge. Understanding cannot be realized by listening or reading about the realization of others. It must be achieved firsthand via substantive, direct perception in the moment.
By means of personal experimentation and observation, we can discover certain simple and universal truths. The mind moves the body, and the body follows the mind. Logically then, negative thought patterns harm not only the mind but also the body. What we actually do builds up to affect the subconscious mind and in turn affects the conscious mind and all reactions.
All creations are one with the universe. Look at the world around you. Can you effectively separate yourself from everything else? After seriously pondering this, most of us rapidly conclude that we cannot. To even make the statement that I exist as a unique entity requires comparison with something else. (If you exist as a distinct being, your distinctiveness is in comparison to other creations. No other creations, no individual you.)