You should exercise your imagination. Exercise it often, strongly, exercise it better – Exercise it, for instance, by changing the small details in a memory. You can alter the arrangement of colors, the location of a specific object, the outcome or even the beginning of a story.
My first exercise, many, many years ago, was to visualize a flower that came back to life retaining the brown and grayish tones, the brittle and asymmetrical texture of when it was completely dry. The exercise could have ended there but I wanted to draw it, describe it in written and spoken word, and even replicate it with live and dead flowers. When I got bored of this exercise (actually, it was a purely imaginative act), I buried it somewhere in my mind, as if it had never happened. Years later, I was able to exercise my imagination with the same memory but from the perspective of someone who had not considered reviving a flower, and much less, someone who waited for a real flower to dry out on the living room table.