Lou Kunzler, who teaches the ‘writing for children’ workshop I attend, had this great suggestion: before you write anything, decide on three words that describe it in a way that will make people want to read it.
Put those words on a sticky note and put it where you can see it as you write, as a reminder that every chapter should fit that description.
For the novella I’m writing, I’d say something like “killer pursuit thriller”—it’s the story of a boy and his father on the run from people who want to kill the father.
That reminds me to make sure to keep up the pressure, to show how much is at stake, and to keep the action thrilling.
You could also choose three adjectives that don’t refer to the plot, just the writing itself, something like “funny, insightful, touching.”
If you are self-publishing you might also find the three words come in handy when you're coming up with the marketing materials for your ebook. However, when pitching or writing a query letter don't use too many adjectives but rather make sure the way you summarize or describe the project suggests those qualities. In other words, instead of writing in a letter to an agent that your book is "funny, insightful, and touching," make your description project those.
I think this strategy could extend to other kinds of goals as well. If you want to improve your health and fitness, what three words describe the result you’re after? Maybe energetic, flexible, strong, for example.
You could also apply it to the process you employ in pursuit of the goal. For you to stick to an exercise regime, for instance, what three words describe what it should be like? Maybe enjoyable, non-competitive, efficient (that is, gets results in minimum time)?