I don't know if today's kids even know what the three R's are. As authors, they can take on a completely different meaning for us.
Reading - I won't preach that you have to love reading, but I hope you at least like it some. I'm sure you will find authors and teachers who will talk down to you from their pulpit and proclaim that you must read, read and read. I'll agree that there is much to be learned from reading other peoples work, especially from the great authors. But I'm not a huge advocate of reading, because you reach a point where you don't want your style to be unduly influenced by someone else's. Plus, there's the cost. Every hour reading could have been an hour writing, but now and then, it's good to pick up a book and see how someone else does it. It's also good to have certain authors or book series that you look forward to reading. I think reading is probably much more important for the younger budding authors, but when you've reached an age that qualifies you for the adjective "seasoned", you'll find life is short and you only want to read what you want to read, and devote more time to writing.
Writing - If you don't like writing, go find something else to do. If you are unsure about what you have written, have it appraised. I attended creative writing courses all through high school and college and a little beyond. Granted, writing was easier in those days, all you needed was pencil and paper. Then, when it came time to share with your class, a typewriter and mimeograph did the trick. No software tools to paste together your story like a comic book, just pencil and eraser. Write something, share it and see what works and what doesn't. Anyone can learn to write, the hard part is the story telling. Story telling is a talent, maybe even a gift. It's not unique to authors, a painter who is a story teller will paint a picture. A painter who is not a story teller will paint a house. It's the same with writing. If you are a story teller, you can write a fictional account to draw the reader in and thrill them with the ending. If not, you can still craft words together, but it will most likely be someone else's story.
Rithmetic - I know, I know, what does arithmetic have to do with writing? I'm not talking about word counts or chapter sizes, it's much more basic than that. And it can be the hardest of all, especially for fiction. We all want to get paid. Getting discovered, or even just noticed, is the hardest part. It uses the other half of the brain too, which makes it harder to do both well. I'm still working on this. If I ever figure it out, I'll let you know.