Written like a riddle, the poem keeps its answer until the very last line: the "he" who follows the speaker everywhere is misery. Until then, "he" sounds like a stalker or a haunting presence, someone who invades nights, dreams and daylight alike. The repeated "He" at the start of each line makes the feeling hard to escape, as if the pressure never lets up.
What stands out is the speaker's mixed feelings. Misery "breaks my soul," yet also "makes me whole," and the speaker admits not knowing who they'd be without it. That's why they decide to write a hymn, a song of praise, for something painful. The poem then widens out: misery isn't theirs alone, and it finds everyone eventually, sometimes on a sunny day or when you're finally relaxing. The mood is heavy but oddly calm, almost resigned. The speaker sounds tired, yet familiar with their pain, even greeting it daily like an old acquaintance.