We are shaped by our thoughts; we become what we think. When the mind is pure, joy follows like a shadow that never leaves. –Buddha
The great Buddha made this statement several centuries ago; the same is being validated by Quantum Physics in the current era. Quantum physics states that all that we see around us is energy and is shaped by what we choose to focus on or observe.
See this classic quantum physics experiment to understand this (from the movie What the Bleep do we know?):
If you are getting the slightest hint of what this mind-boggling but factual experiment is, then you would start seeing that your current reality is an outcome of what you have been focusing on consciously or unconsciously.
Thoughts are the building blocks of manifested reality; at the deepest levels of ourselves we are purely consciousness, that which we can call divine energy or Life itself, and the outer levels we are mind and body.
At an individual level we are an individual, i.e. an individual spirit, individual mind and Individual body.
At the absolute collective level we are the Universe i.e. the universal spirit, the universal mind and the manifested Universe.
The waves of the Sea are the same as the Sea, but the wave has a separate identity from the Sea, similarly we are one with the Universal Spirit, but we have an identity separate from the Universal Spirit. But in actuality we are one with the Universe.
All the Individual Minds of all the individuals together collectively is the Universal Mind, the supreme spirit from which all individual spirits come forth is the Universal Spirit, and the Manifested reality is the Universe.
In Spirit you are ONE with the Universal Spirit and can create any reality you would like using the exact same principles of creation used by the Universal Spirit.
But first you must understand this principle,
Whatever though or idea you choose to be aware of is passed on to the sub-conscious mind, the sub-conscious mind sees no difference between awareness based on a thought or actual reality, and it sees them both to be true.
When your vibrate the same energy of enjoying the fulfillment of your desire the sub-conscious mind considers this to be true and puts forth means to manifest this in the Universe.
The sub-conscious mind will now interact with the Universal Mind and work the means to make this true.
In day-to-day life this can be seen as, you are the Observer as Consciousness and what you are being aware of is the manifested reality (i.e. your thoughts, your body and your surroundings, your interaction with others).
Whatever thoughts you focus you awareness on “consistently” will manifest into reality by the principle of the Law of Attraction.
What we are today comes from our thoughts of yesterday, and our present thoughts build our life of tomorrow: Our life is the creation of our mind. – Buddha.