In fiction you can make up everything to create the feeling. You can manufacture a story with whatever tools you want. With nonfiction you have to rely on what actually happened to describe what you're feeling. That's hard. You have to know what will feed into the emotion you're trying to convey. And that's hard because you don't necessarily know what causes your emotions.
I am often criticized for spending too much time off the ice, but if you were in my shoes, you'd see how necessary it is.