You have to go full throttle; passion will pull you through. It's a virtuous circle; the more passion you have, the more you get.
Thinking creatively and passionately drives motivation, and your motivation drives creative thinking.
There is a very famous film of Picasso painting live. About halfway through creating an effortless masterpiece he says “ Ca va tres mal” (it’s going very badly). Even someone like Picasso struggled to get a painting to go where he wanted it to go. It’s his self-belief, confidence and self-trust that allows him to work through the “bad” stage and experience that tells him that he can make it right. I’m certainly not in that league, but that helped me to understand that I should push through (although sometime you can try too hard and take a sketch too far) and trust my instinct.