Trust that each word that emerges is the correct and appropriate one. Don't judge.
Trust your imagination.
Trust past your imagination, which has its own limits, and trust those creative sources that guide and inspire you.
Trust the unknown.
Trust the depths of a passion you may not even know you feel.
Trust the light that kindles your faith -- your faith that one word will lead to the next, that two words will form a cogent and coherent thought, that each sentence will form part of a whole that is not visible in the writing of it.
How about you: Do you think trust is a necessary part of your writing?