Bodily/internal energy and external energy often intertwine.
In fact it is this meeting and conversion of the 2 that is often what generates a good deal of psychic abilities.
Example:
Telepathy- a difficult psychic ability to lessen restrictions of multiple persons' mental frequency; reading minds or letting someone else read yours.
This is, mental internal energy forcing to replace surrounding external mental energy (or mental energy of another).
Energy can also be considered in aiding divination when speaking of its focus points or rather, chakras.
There are countless chakras that can and often are assimilated for use in daily activities. But the there are 7 in particular that are used most.
Root Chakra
Sacral Chakra
Navel Chakra
Heart Chakra
Throat Chakra
Third Eye Chakra
& Crown Chakra
Each of these points are massive generators of internal energy. Balancing them and keeping them clean helps with aspects of our lives such as personality and temperament; those who have clean, balanced chakras are typically the happiest of people. Not only this but they have a significant affect in our magic abilities, progress, and potential.
Hence why energy is considered the root of magic; manipulating it causes things to happen in magic- spell, rituals, prayers, and such are all ways to simply manipulate various types and forms of energy into causing certain events and creations.