"It's suppose to be hard. If it wasn't hard, everyone would do it. It's the hard that makes it great." - Tom Hanks's baseball coach in A League of Their Own
As much as I love this quote, I think they left something out: "It's the hard that makes it great when you succeed." If it was just hard and there was no reward of any kind, well, who'd keep going? Let's be honest here.
However, the reward doesn't have to be "big" to make it "great." It doesn't have to be obvious to the world, like a making sale or a list. The reward can be as "small" as the first time you finish a scene and think, "Yes! That's good!" (Although I could also argue that the first time you really believe you have talent is a huge step in your evolution as a writer.)
I've had many people say to me that they'd like to be writers. What they'd like is to have written. They don't want to do "the hard." But when you do the hard work, and you succeed, by whatever measure, large or small, obvious to the world or only to you, it is great. And that's what keeps me going through the hard.