IMO, we just cease to exist and there is nothing more. Humans cannot fully comprehend the lack of existence (or at least I think most of us can't), so they mentally create these afterlives as a continuation of our life. I think, and I may be very wrong, our brain works with associations, and since we've never experienced the lack of our existence some of us think our conscience will never cease to exist. I don't think the lack of my existence is just some sort of blackness for eternity, it'll be like before I was born: nothing at all. I won't be there, conscious, thinking about how boring "afterlife" is. But again, these are just my views, they might be right or they might be wrong.