Another favorite book on writing is The Courage to Write: How Writers Transcend Fear by Ralph Keyes. I particularly like the following paragraph(s), which I've divided in two although the author didn't.
"The longer I wrote, the more my admiration has grown for those who set out on this journey. They are apprehensive and should be. Writing is a daring act. Any time we put so much as a word on paper we're in jeopardy. (What if someone thinks we could have chosen a better one?)
"Whoever writes for public scrutiny is subject to a form of what psychologists call 'performance anxiety.' Polls routinely confirm that public speaking is our number-one fear. (Dying ranks sixth according to one such poll.) Writing is merely public speaking on paper, but to a much larger audience. For some, writing to publish is even more daunting than speaking in public. Spoken words blow away in the wind. Published ones last as long as the paper on which they're printed."
And Mr. Keyes quotes some other writers in his book, as well.
"If we had to say what writing is, we would have to define it essentially as an act of courage."
"Speech was given to man to disguise his thoughts."
"Anxiety is the essential condition of intellectual and artistic creation and everything that is finest in human history."