I can honestly say that I don't really use my imagination very often anymore. It's sad when you think about it.
I remember as a little girl drawing a new futuristic sleeping bag that had all sorts of hidden compartments and secrets. I also drew a cabin built into the side of a mountain behind a waterfall.
Tonight, I had a student come in that is applying for the ImagiNations 2012 Disney Competition. Teams have to consider the following scenario:
Imagine it’s the year 3011, Disney has entertainment experiences all around the world, many which don’t even exist today. The human race is finally living on the moon and Walt Disney Imagineering wants to be the first one to provide entertainment and/or recreation to the new citizens there.What would you imagine that this new Disney experience could be?
This student had a TOTALLY awesome idea. Just wicked... it's an "experience" that doesn't exist ANYWHERE at this time. It was such a flipping cool concept. My brain was delighted thinking about all the possibilities of his experience.
However...I really struggle trying to come up with my own original idea. In fact- I'm not very good at coming up with original ideas about anything, really.
So how is your imagination? Is your brain muscle strong? 
What do you think your Disney experience would be?
Do you know of any neat imagination exercises?