“Walking in light” is a metaphor for a state of being that is probably most accurately described as being in a state of grace. Walking in light is different for different people in different circumstances.
For the ancients, a state of grace was being in accord with The Way, Buddha, nature, Atman, What Is. In the Abrahamic traditions (Judaism, Christianity, Islam), it would be called walking with God, being filled by the Holy Spirit or being in communion with Christ. In this state there is no conflict between the heart, mind, body and soul; or, if there is a conflict, it is apparent, external and inconsequential. The observer, the true self, sees reality just as it is. In this state there is a sense of awe, wonder, gratitude, and boundlessness. The conflict is minuscule in comparison.
Walking in light is appropriate in that reality takes on a luminous quality. There is also a certain lightness – many things that seemed so serious, heavy, dark, foreboding, or scary are no longer seen this way. Instead, there is infinite possibility and reality – and there is nothing to be afraid of.
At the same time there is also an extraordinary simplicity. Everything just is, as it always has been and always will be. In this way life itself is analogous to a dream. Awakening from the sleeping dream and the limits of the dream seem small compared to life itself. There is a sense of a much larger reality than what we were able to imagine during our dream state.
When we awaken into reality – true reality – we realize that separation is an illusion; nothing exists independently, nothing real is born or dies, and all of our pain, worries, fears, and suffering come from the fact that we are looking at it from the small perspective of our personal (egoic) self.
Once released from the small self, the true self manifests as equal to infinite reality – as far as the human mind can fathom.