Okay, I'll agree that inspiration is over-rated.
The novel I'm working on now started from commenting on something else, which had a blacksmith's daughter as a heroine. It made me wonder if it would be possible to have a blacksmith as a romantic hero. Once I had decided that, most of the started to fall into place. The time dictated a lot of the setting, and I had to dream up a heroine who was a good match for him, and a mystery they needed to solve together.
Very little of it was inspiration, most of it was research and necessity.