Knowing I love to write and having something to write about are two different things. I have an idea of what I want to write, but not the actual topic.
I've intentionally put some distance between book 4 in my series and now. I've done a lot of freelance writing projects and as usual will know when I'm supposed to write that next book. I'm not waiting for invisible inspiration to strike, but I'm also not forcing an idea either.
Everyone's writing journey is different. Some people can crank out book after book. Some authors wrote one, maybe two profound novels and that's it. I don't yet know where I rank. I just know I like for the idea to push me, versus me pushing the idea.