Read! There is a saying that goes ‘a man who reads lives a thousand lives, a man who does not lives only one’. The key to imagination is experience and exposure. Something different that is unique and profound. The more ideas, concepts and experiences one exposes himself to the grander his imagination. This does not involve reading only fiction but also about history and factual accounts as well.
This brings us to our second point, imagination does not necessarily mean creating a whole new world for oneself, rather one could create an element of fantasy in the real world itself. What if every garbage collector was an FBI agent or so on.
The essence of imagination is to create something interesting out of the mundane and the best way to do this is to combine something unbelievable or ‘cool’ with something boring and mundane. So if one really wants to expand his imagination then practice sitting down in a park or by the side of the road and creating stories for each person or thing. A traffic light could be a camera monitoring cars, the police officer could be a costumed vigilante by night. Once you begin practicing this, stories will automatically pop in your head and you will find yourself in a completely new world.
Play video games as they allow users to express their imagination and is a great simulator for those who want to see their ideas come to life.