K. Tempest Bradford would like to challenge you to "Stop Reading White, Straight, Cis, Male Authors for a Year."
Let me first and foremost say, I support this idea.
Secondly, it will not be difficult.
You could easily read a book a day and only read women writers. I actually did this spontaneously when I was in my youth, probably somewhere in the mid-1980s (and continued well into the early-1990s), when it was also still very easy to find women writing SF/F. In fact, we were just coming off the great boom of the New Wave and I simply spontaneously and naturally drifted in the direction of books with women's names on the cover, This was when I read nearly everything by Anne McCaffery and Katherine Kurtz. I supplemented with Mercedes Lackey and Anne Rice and Joan Vinge and Pat Cadigan and Pat Wrede and Emma Bull and Ursula K. LeGuin and Marge Piercy and Elizabeth A. Lynn -- many of whom were also writing ABOUT gender and sexual orientation/fluidity back when most the mainstream had no idea what genderqueer was.
But, even if you limited yourself to books written in the last few years, this would also not be difficult. The largest percent of fiction written and bought in the United States published by New York publishing houses is by women for women. It's this genre you may have heard of called: Romance --which also has an ENTIRE SUB-GENRE DEVOTED TO STORIES BY AND ABOUT PoC. Yet, even if you limited yourself to science fiction and fantasy, this would not be hard.
As I've said previously, the challenge I've issued myself is to read all the books nominated for awards this year. So far I'm only just finishing the list for the PKD. Out of six nominees, 4 were by women. Just to make that clear, a THIRD of the books nominated for the 2015 Philip K. Dick award are by women (and one of the women is also in translation.) The Nebula Awards nominees, which were just announced this past week, didn't do as well. Of the six nominated novels, only 2 were obviously by women, but one of them is in translation (and, honestly, given my lack of understanding of Asian names could also be by a woman). By Tempest's criteria, that's still HALF of the nominees you could read.
So far we have seven books you could read right there. If you read a book a week, you're already deep into your second month.
That's without even really trying.
Tempest's list is a fine start and, if you've not heard of any of those writers, you really ought to go ahead and put them on your list ASAP. But, she's certainly not even scratched the surface.
I'll say again, I think this is a fine challenge. If you've never done anything like this in your life, you really should. Once you've done it, though, consider allies also. If I limited myself to these criteria my whole life, I would be fine (and would never have lacked for books), but I would have missed out on a story that blew my small town mind back in the 70s (and even more so when I discovered it was written in 1953). And that would be Theodore Sturgeon's short story, "A World Well Lost." Which is basically about bigoted assumptions people make and how wrong homophobia is. It was the first time I'd read a story where the protagonist was a gay man and it expertly played with my assumptions that everyone was straight. This is the kind of story that, even though it was written by an old (dead now) white guy who I presume is straight, EVERYONE SHOULD READ. I taught this story in class and I can say it doesn't entirely stand the test of time. The prose is very 1950s, which reads somewhat clunky to a modern ear, but the idea is still mind-blowing.
So, you know, yes, but there are diverse books EVERYWHERE these days. You just have to look around.
Do we need more diversity? Yes, always. But could you do this without breaking a sweat (even just within SF/F?)? YES.
Hell, I've got about 15 books by a queer woman just sitting here on my desktop (oh, because THEY WERE WRITTEN BY ME)... some of them are even award winners. ;-)
Edited to add: You know what would be a more interesting challenge to me? Read only comic books, graphic novels and manga written by woman/PoC (well, with manga, you'd have to close the loophole of PoC or you could read any manga you wanted.)