To get a good feel for a mental energy step and a physical energy step, and how they relate, we go to math and physics.
Einsten said, "everything is vibration." In the physical universe, all matter (particles) can be described as waves (vibrations) according to the Schrodinger Equation. All energy can also be described as waves.
This Schrodinger matter wave corresponds to a
particle traveling freely through
empty space. (Wikipedia)
So to experience the truth of Einstein's feeling of oneness of everything, notice how your thoughts and body movements are also vibrations.
Vibrations in physics are defined as the vertical (sine) and horizontal (cosine) functions of a circle (a vector continuously rotating around a central point).
The horizontal mental step (cosine function) is going from planning (forebrain) to seeing the results (occipital lobe), and back again. The vertical mental step (sine function), is going from thinking (brain) to doing (body), and back again. Up and down movements, and front to back movements, when repeated are called vibrations. Specifically, the horizontal mental vibration is: planning ... seeing the results ... planning ... seeing the results ... planning ... seeing the results ... And the vertical mental vibration is: thinking ... moving the body ... thinking ... moving the body ... thinking ... moving the body ...
The horizontal physical (foot) step (cosine function) is pushing your body forward and then moving the foot forward to take the next step. And if you're stepping backwards, the opposite happens. The vertical physical (foot) step (sine function) is pushing your body up, and then raising your foot to take the next step. Since the foot is making up and down movements repeatedly, and front to back movements repeatedly, these are (coupled) vibrations.
In the app Energy Step, which helps you get a feeling of unity of things, the awareness indicator stops periodically at vertical locations relative to the spine. These are called chakras by Indian philosophers.
Screenshot from the Energy Step App.
Chakra means "rotating wheel." One way we experience awareness at any specific location as a "wheel," or function of a circle, is that when the radius vector is pointing below the horizontal, we are not aware (or conscious), and when it is above vertial we are aware at that location, like night and day on Earth. This is vibration awareness at a stationary point. We are (more) aware when there is light there, less aware when it is mostly dark there.
It's the stroboscopic effect of awareness at a point, due to the pulsating nature of neurons singly and collectively. It's like when you listen to a sound intently, you can hear it getting louder and fading away quickly many times duing a sustained note. This awareness can be experienced at any body location when you hold your attention there.
Feeling that every experience, mental and physical, is vibration doesn't mean we know as much as Einstein did, but it helps us get an intuitive feeling of how everything we are aware of vibrates the same way every particle in the Universe vibrates.
Walking and listening in a relaxed way with the Energy Step app helps you feel this not just intellectually, but in your body.