As a writer, I've never suffered from writer's block, but I've talked to many writers who have. Their explanations seem to always include these phrases, "I just can't think of anything GOOD to write.", "I've written a paragraph but....I don't know where to go from here. I don't know what else to say.", and "You can pull water out of an empty well. I'm on empty!"
I'm just thankful that I've never gotten to that point of being empty, or unsure of how to proceed, or unable to think of anything good to write. I honestly have the opposite problem...finding time to write everything I want to write! haha