The speaker begins with a kind of list of survivals: the winter pain, the wind pain, the wish pain. Each one is named briefly, almost casually, as if these hardships are behind them. The repetition of "pain" makes them feel like items on a tally, and the shift from weather to "wish" suggests that longing hurts in its own way, just as cold does.
Then the poem turns. Having come through all that, the speaker admits they still can't write unless the pain is much bigger, "great as two stones / or a rusted bed." Those images are heavy, solid and oddly domestic, and they suggest something dull, stuck and worn out rather than dramatic. The mood is dry and wry, with a hint of unease. The speaker seems to be poking fun at the idea that suffering fuels art, while also quietly admitting it may be true for them. Ordinary pain isn't enough; the poem wants something with weight.