The harder you pull your fingers out of a Chinese finger trap, the more tightly they are trapped.
Creativity is the same. The harder to press, the more difficult it is.
The best way to be creative is to relax.
In between times when you need to be creative, work on becoming more interesting by reading books, traveling places, and honing skills (especially outside of your craft!)
Then, when it’s time to be creative, relax, and let your mind’s intuition and instinct take over.