Ever try to imagine those things? You'll probably find your imagination doesn't work as well as it used to. I can still picture things, but they're not as real to me as they used to be. Dreams are part imagination. I think as we age, daily life gets in the way of the wonder we used to feel. Maybe our aging subconsciouses are too loaded down with life to dream so vividly. Try watching some movies or shows for younger people, or reading a fantasy novel. Maybe that'll help your brain get some inspiration.