The body of light is the body each of us will inhabit when we've finished learning the lessons of incarnation in dense matter and can move on to more interesting things. Most occult schools teach exercises to help students develop the body of light -- for example, the Middle Pillar exercise has this purpose among others. Those practices have to be combined with other forms of spiritual development, however, because the body of light alone is not enough -- the soul must achieve reflective self-consciousness and awaken on the mental plane before it can inhabit the body of light in place of a body of matter.