[Compare the] ease of remembering versus the difficulty of imagining. Most of us can remember who we were 10 years ago, but we find it hard to imagine who we’re going to be. And then we mistakenly think because it is hard to imagine, it’s not likely to happen. . . . [W]hen people say “I can’t imagine that, they are usually talking about their own lack of imagination and not about the unlikelihood of the event they’re describing.”