I have the same problem of not having enough imagination!

I have tried exercises like imagining throwing a ball with my left arm and hitting a bucket 5 meter away over and over for a week before testing if there is any improvement in my left arm throwing (try it ;-)

I have tried piclking 2 or 3 words randomly from a book, then combining them in different ways to see if I can come up with new ideas (it works well in practice -- but I fail time and time again in the real world ;-)

I have tried watching TED taks (on the web) to see if they can seed new ideas or new ways to imagine things (often, they do give new ways of looking at things, but not often they are what I am looking for ;-)

...;-)