Back when I was thinking about what makes a good goal, I asked myself what my goal was for writing, and the first thought that came to mind was "I want to write a good book." A few moments' thought led me to the conclusion that this is really not a good goal.
For one thing, what is a good book, anyway? Who gets to decide? Me? Other people? God? Well, yes, God, but how can I know if He thinks it's a good book? I suppose if He was intimately involved in its writing you'd have to conclude He thought it a "good book" but this whole concept just seems bizarre when you think of it as from God's viewpoint. He called me to write the thing. He's promised to provide me everything I need to do it. He's promised to enable me to do it, and I believe He does so. So... if all that is true, than "good book" just seems irrelevant. If it's what He wanted me to do, then it must be good.
And here's the corollary: If I am filled with the Spirit and writing from a soul prepared with doctrine and with craft (preparation He provided) then it would be impossible to write a bad book. That doesn't mean people will necessarily like it. Some might. The majority might not. Many, in fact, might reject it outright or with general disinterest. Is that a bad thing?
God had Jeremiah write some things that his "readers" didn't much like, either, and in fact, outright rejected. They made him a laughingstock, and sang mocking songs about him. Moses said things at God's leading that his congregation didn't like, either. A few of them tried to depose him. Paul said things in the power of the Spirit that people disliked so much they stoned him. And last we have Jesus, the only perfect man, who did only good, and the people rejected him, chose the criminal Barabbas over Him and crucified him. So you obviously cannot base the value of your work on its public reception.
That's hard stuff for a perfectionist mind that builds its worth on what others think. But it's true stuff and the perfectionist, as I've already established, is deluded and masochistic. So "writing a good book" is not a good goal, nor even an achievable goal. I must come up with another, better goal. How about, "write a book"? It's measurable, it's doable and you know exactly when you've accomplished it!