What happens when you do that? Well, for me what happens is the realization of the value of being pragmatic. Truth is, like Descartes said, we can't really know anything but our own existence, and depending on your definition of existence, even that can be questioned. But what is the value in that? Now when I know I know nothing, is it a good basis to live my life upon?
My answer to that is no, it's not a good basis to stand on. Instead I choose to approach it pragmatically, or as an engineer if you prefer, "I accept my perception of reality* as real" and "a useful fact is information that can somehow be used to predict the future"
But then, I tend to like answers more than questions, I guess it comes included with my engineering degree.
* Not meaning that everything I perceive in a given moment has to be real, rather that my understanding of the world is my best guess of how things are.