What makes us so certain that we're conscious?

In the attention schema theory (AST), having an automatically constructed self-model that depicts you as containing consciousness makes you intuitively believe that you have consciousness. The reason why such a self-model evolved in the brains of complex animals is that it serves the useful role of modeling, and thus helping to control, the powerful and subtle process of attention, by which the brain seizes on and deeply processes information.

Automated summary

In the attention schema theory, having a self-model that depicts consciousness helps in controlling the brain's attention process, leading to the intuitive belief of consciousness.