Reality shifting is a beautiful and amazing phenomenon. Explaining it to its full extent is nearly impossible due to the numerous possibilities and theories. However, let me simplify it for you so that you can partake in this life-altering experience.
The universe is incredibly vast, comprising an infinite number of different realities, possibilities, and worlds. Each reality, world, and life is unique, varying from subtle to drastic differences. This means there are realities where humans may have green skin while everything else remains the same, or there could be realities where everything is profoundly different, such as human life not being carbon-based.
Just as vast as the universe is, so is our consciousness. Our consciousness spans this infinite realm of possibilities, resulting in a version of us in each and every reality. While you may be a regular civilian reading this now, somewhere out there, you might be a celebrity, a dedicated meditator, or even someone less admirable.
During reality shifting, we choose to shift our awareness from our current reality to a different aspect of our own consciousness. Since our consciousness already resides in all these different realities, it's not accurate to say that it's impossible to access them. Shifting is simply waking up with a different perspective, a different version of our own life.