Hello (Insert name or psuedonym of choice in the following blank: _______________),
I've tried and failed at writing various novels on differing topics, and the reason I've failed is because I grew bored of their topics/I couldn't get an idea for the next chapter. Lately, I've been writing a Sci-Fi novel, and it is going along smoothly. But I'm writing in fear of writer's block settling in and keeping my topic from being finished. Also, I have unknowingly been partially copying The Hunger Games, and I still want to keep my plotline the same. (However, I can settle for a few MINOR would have used italics there, but there aren't any
changes.) I would much appreciate any feedback.
In the end, it's not the ideas or the topic that maintains a person's interest in a story (including the writer's). It's the characters. Make your characters and their conflicts/growth emotionally engaging. Make us care about them and everything else will follow.
Also, it helps to have an outline, because the middle of novels is always the place where the writer has to do the hard slogging. That's where, if you don't really care about the characters, it's easy to give up. An outline will at least help keep you on track.
Finally, if your story is enough like another book that other people might accuse you of copying, change it. Keep what's essential and unique, but change the idea.
When making changes to a story, always change it in ways that make you even more excited about it.