From a fine remembrance of Derek Walcott by Bert Almon:
He repeatedly said that forms actually free the imagination. He had advice for writers when metre falters: “If the metre peters out, stop. Solve the problem, it’s a gift of discovery. Start a new sentence.” As for rhyme, he stated that “every line of verse wants to rhyme. Every line expects to be coupled.” But he also said that “Rhyme is a precipice,” because you might not find the right rhyme. As for diction, he said this to Alycia Pirmohamed: “This is the work of the poet: finding the right word. It might take you days or weeks before it comes to you. The only advice I can give you is to find a high place with an open window, and walk towards it.”
These days, the main difficulty is finding “a high place.”