One thing I've found that I can do that I really enjoy is rereading my own writing, earlier stories and novels especially. It induces mental time travel, the same way certain songs you hear on the radio do ... the whole thing returns, an eerie feeling that I'm sure you've experienced.
Philip K. DickI am Ubik. Before the universe was, I am. I made the suns. I made the worlds. I created the lives and the places they inhabit; I move them here, I put them there. They go as I say, then do as I tell them. I am the word and my name is never spoken, the name which no one knows. I am called Ubik, but that is not my name. I am. I shall always be.
Philip K. Dick