Think positively. Forget all the reasons why it can't work, you can't do it, it costs too much, there's not enough time, etc. For the moment, who cares? Instead, focus on positives—solutions, opportunities, possibilities, rewards— to "unblock" your creativity.
Judge not. The worst impediment to creativity is the fear of failure. Of not pleasing the creative director. Of having someone laugh at your work. If you believe you have a viable, creative idea that does the right thing for the right reasons—and you, indeed, have reasons—why judge yourself as being wrong before you show your work to anyone?
I recently read How to be More Creative by David Edwards which sums up three major misconceptions about creative: (1) being creative means being artistic; (2) creativity demands great skills; and (3) creativity is a function of intelligence. The truth is you don't have to be a Monet, you don't have to have spent years studying under the Masters, and you don't have to be brilliant to be creative. It's a part of all of us.