«أَيَّامَ أَسْحَبُ مُطْرَفِي فِي رَوْضِهَا»
In those days I trailed my fine cloak through its gardens.
Asḥabu is a present-tense verb used vividly within a recollection of the past. Muṭraf denotes a fine garment or cloak; rawḍ a green garden.
The trailing garment becomes an image of ease, status and youthful confidence. Even if not taken as a literal daily routine, it effectively shows the life the speaker believes he has lost.
Burd al-shabāb makes youth into a garment, giving a life stage a tangible image.