Everything is energy whether we see it or not - there is the physical and the non-physical. Science is starting to bridge the gap of understanding between the two through the study of quantum physics. There is the physical biological body and non-physical energetic body so somebody may hurt our physical arm and they may hurt our feelings or say something that causes mental anxiety. When it is broken down, energy plays a part in everything and everyone.
Living in a dual existence means there are 2 sides to every coin. In metaphysical energetic terms we often talk about this as positive and negative or high and low vibrational.
When we talk about raising our vibration through energy healing, we are seeking to vibrate towards stronger and bigger scale vibrations. Equally, when you surround yourself with lower vibration activity, thoughts or conversation you will align to similar stronger lower vibrations. As an example, when you are with someone negative, have you noticed how drained and negative you begin to feel? this is because you are starting to vibrate and align to them (entrainment).
Energy always vibrates like a ripple affect, like when a pebble is dropped in water so, when energy is passed through a person, it vibrates through the person and alters the vibrational state. The ripple effect vibrates beyond the person out into their aura and further, so collectively we are all affecting one an another's energy vibration and therefore the universal energy.
To maintain your energies at a high vibration, you need to consciously be aware of how to proactively do so. If you are super sensitive to the subtle non-physical energies, this becomes even more important to avoid taking on low vibration from others, the environment and other external forces.