What's so hard about that first sentence is that you're stuck with it. Everything else is going to flow out of that sentence. And by the time you've laid down the first two sentences, your options are all gone.
Writing nonfiction is more like sculpture, a matter of shaping the research into the finished thing. Novels are like paintings, specifically watercolors. Every stroke you put down you have to go with. Of course you can rewrite, but the original strokes are still there in the texture of the thing.
When I was in fact a child, six and seven and eight years old, I was utterly baffled by the enthusiasm with which my cousin Brenda, a year and a half younger, accepted her mother's definition of her as someone who needed to go to bed at six-thirty and finish every bite of three vegetables, one of them yellow, with every meal.
You think you have some stable talent that will show no matter what you're writing, and if it doesn't seem to be getting across to the audience once, you can't imagine that moment when it suddenly will. Gradually, gradually you gain that confidence.
When I went to San Francisco in that cold late spring of 1967, I did not even know what I wanted to find out, and so I just stayed around a while and made a few friends.
Writing fiction is for me a fraught business, an occasion of daily dread for at least the first half of the novel, and sometimes all the way through. The work process is totally different from writing nonfiction. You have to sit down every day and make it up.