"I've always believed that the imagination is a spiritual quality that, like memory, can be trained and developed." -- Luis Bunuel
Yes. Agree with passion. The imagination can be developed.
So prior to writing a script, or during, or while in production, train and develop your imagination. How? Keep a journal. An intimate, reflective, honest journal. This will train you to think, observe, and yes, use your imagination.
Think of the imagination as a muscle. It needs to be used. Keeping a journal will help.