What to read?

People joke about "so many books, so little time." You can even buy a t-shirt with the phrase splashed across the front. But it's true — there are so many books, and for me, who just turned 68 . . . well, I can do math. And so I find myself increasingly wanting to read very selectively, and only the books that will push me the most as a writer, and as a person. How do you decide what to read, or what to skip?