The detachment mentioned in the Seven Valleys is not absolute detachment. It is detachment from all things save God. This detachment occurs because one becomes so enamored of God, there is room for nothing else.
Anyone who has fallen in love can relate to this experience. In those moments of communion with the beloved, everything else in the world disappears – time, place, consciousness of self, etc. – as if the lover were carried away on a sea of bliss, tossed by waves that know nothing, wish for nothing.
To attempt detachment by any means other than absorption in God is a terrific task. I think the Writings indicate that so All-Sufficing is the nature of God (as revealed by His Manifestations), that in His presence we would not find detachment rare at all, or precious, but simply the natural result of devaluing of every lesser thing. As Rumi describes it, the invisibility of the candle when placed before the sun.
To find this, we must be willing to cease paying so much attention to worldly things, or cherishing the hope that they will grant us any peace or happiness. This is not “detachment” yet, but a prerequisite along the Path. The more time we spend in prayer, and reflection on the transient nature of the world, the more we discover that only the former offers anything in the way of peace.