He flicked his wand, a silent Lumos charm illuminating the space aroung them, and levelled with her, and they walked up the stairs in silence, soft padding of her bare feet against stone overpowered by clicking of his shoes.
If we try to define it, we can say that it is a state of existence with a clear sense of purpose, deep personal fulfilment, and the belief that what you are doing matters to you and to the world.