Update: See Babies, Bathwater and Goal-Setting for more on goals, including concerns about their counter-productive impact.
The goals we set for ourselves have a significant influence on our performance, and this is as true for self-coaching as it is for any other meaningful task. Edwin Locke and Gary Latham are two of the world's leading researchers on goal-setting, and in 2006 they summarized the results of roughly 400 studies conducted over the course of 25 years in a short, pithy article, New Directions in Goal-Setting Theory [PDF]:
So long as a person is committed to the goal, has the requisite ability to attain it, and does not have conflicting goals, there is a positive, linear relationship between goal difficulty and task performance.
So when we're A) committed, B) able and C) unconflicted, we owe it to ourselves to aim really high. I'm not suggesting that these conditions are easily met. Two out of three, sure, but meeting all three can be a high bar. And, as noted below, at times aiming too high is counterproductive, particularly when we perceive a difficult goal as threatening. The key is aiming just high enough.
My Personal Goals
Among the goals I've set for myself are 1) exercise, meditate and write every day, and 2) eat and drink moderately and get 7 hours of sleep on a regular basis (in my case, 70% of the time). I strive to achieve the first set on a daily basis because I'm committed, able and unconflicted--no counter-goals stand in my way. My target for the second set is lower because while I'm certainly committed and able, I do have some conflicting counter-goals: While a reasonably healthy diet and decent sleep hygiene are important to me, I also derive a lot of pleasure from good food and drink, and I often stay up late to read or work or just to have fun. So in the former case I have some stretch goals that push me to accommodate them, and in the latter case I have some easier goals that accommodate me.
So how am I doing? I wrote about exercise the other week in a post on self-assessment; I'm only at 85% for 2012 so far, but I hit 92% in Q2 and 100% in June--pretty good! Meditation: I'm at 72% for the year, 85% for Q2 and 97% for June--again, a positive trend. I only started tracking writing in June: 90% for the month, a respectable start. A moderate diet: I'm at 65% for the year, 68% for Q2 and 60% for June--room for improvement, but not bad. And a good night's sleep: 54% for the year, 53% for Q2 and 40% for June--obviously, something needs to change here. But on the whole, I'm pretty damn happy. (As I've noted before, I use Don't Break the Chain to track my daily activity, and at the end of the month I just transcribe the results into a spreadsheet.)
Goals and Performance
How do our goals affect our performance? Locke and Latham identify 4 factors at work:
 High goals lead to greater effort and/or persistence than do moderately difficult, easy, or vague goals.  Goals direct attention, effort, and action toward goal-relevant actions at the expense of nonrelevant actions.  Because performance is a function of both ability and motivation, goal effects also depend upon having the requisite task knowledge and skills.  Goals may simply motivate one to use one’s existing ability, may automatically "pull" stored task-relevant knowledge into awareness, and/or may motivate people to search for new knowledge.
So goals encourage us to work harder and longer, and when they're difficult to achieve they push us even more. Goals compel us to prioritize and avoid spending time and energy on irrelevant tasks, suggesting that they help us triage and distinguish between relevant and irrelevant tasks by attaching importance to the former and devaluing the latter. Goals obviously aren't a panacea, and we're unlikely to achieve them if we lack the necessary knowledge and skills. But even when those qualities aren't in abundance, goals help us make the most of what we have while spurring us to learn more and enhance our skills.
I certainly see the impact of goal-setting when I look at my progress with regard to meditation. In February 2009 I wrote, "I fully appreciate the importance of...meditation...But I still can't bring myself to actually do it on a regular basis." Then in May 2011 I got serious and decided to try meditating daily; as of January of this year, I was making a go of it, but still had difficulty: "Looking back at the last six months of 2011...I meditated just 45% of the time." And now I meditate just about every day; I'm highly motivated to do it, I prioritize it over uses of my time, and I find it much easier to do, which I take as some sign of increasing skill.
Locke and Latham also identify 4 factors that influence our goals' effectiveness:
The key moderators of goal setting are  feedback, which people need in order to track their progress;  commitment to the goal, which is enhanced by self-efficacy [defined as "task-specific confidence"] and viewing the goal as important;  task complexity, to the extent that task knowledge is harder to acquire on complex tasks; and  situational constraints. With regard to the latter, Brown, Jones, and Leigh (2005) found that role overload (excess work without the necessary resources to accomplish a task) moderates goal effects; goals affected performance only when overload was low.
So effective goals will generate feedback on our progress, heighten our sense of commitment, relate to complex tasks and be supported by the resources we need to accomplish those task.
While I have only one month of data on my commitment to write daily, it's noteworthy to me that I hit 90%--not perfect, but good enough to make me happy. My effectiveness at achieving this goal was clearly affected by the feedback I get on my writing from a range of sources: Twitter followers, various links, and, perhaps most importantly, the friends and colleagues who take the time to express their support. The more I write, the more important writing is to me--it's certainly something I'm deeply committed not only as a means of self-expression but also as one of the best ways I know to improve as a coach. While I find writing deeply fulfilling, it's also one of the hardest things I do--fulfilling doesn't always mean fun when it comes to demanding work. Finally, in fairness, I usually have more time for writing in June because of the end of the academic year at Stanford--let's see how I do in October. So obviously a constellation of factors enhanced this particular goal's effectiveness in my life, and hopefully I can keep them in place going forward.
Three additional points from Locke and Latham:
 Sometimes specific, difficult goals do not lead to better performance than simply urging people to do their best.
When tackling a new, complex task, focusing on a performance outcome may cause us to prioritize the goal and lose sight of the bigger picture, i.e. why we set the goal in the first place. In these cases, it may be preferable to identify learning goals which put the emphasis on acquiring the skills needed to achieve a given task.
 Assigning hard goals may not be effective when people view those goals as threatening.
When we see a difficult goal as a "challenge," we focus on the possiblity of success and the utility of effort. However, it's also possible to see a difficult goal as a "threat," which shifts our focus to the possibility of failure and undermines our performance. As always, our mindset is a critical factor.
 Goal progress and goal importance [can be] strong predictors of feelings of success and well-being.
But in the relevant study cited by Locke and Latham, only people "who perceived their goals as difficult to obtain" reported these positive feelings. In the right circumstances, stretch goals just feel good.
Escalation of Commitment
One final topic related to goal-setting that I'll touch on briefly: There's some fascinating research on the "escalation of commitment," a phrase coined by Barry Staw in his classic 1981 paper, The Escalation of Commitment to a Course of Action [PDF], which explored why people continue to follow failing courses of action when they would have been better off cutting their losses. (Theresa Kelly and Katherine Milkman also have an entry on the topic [PDF] in the upcoming "Encyclopedia of Management Theory.")
Most of this research understandably focuses on "vicious cycles"--the dynamics that reinforce our commitment to failure--because we (mistakenly) assume that when things are going badly and getting worse, we'll stop and choose another path. (We often don't.) But there's also value in understanding how these dynamics can be applied to support effective goal-setting and reinforce our commitment to success. The dimension that seems most relevant to goal-setting is what Erving Goffman called "impression management" in his 1959 book, The Presentation of Self in Everyday Life. Kelly and Milkman write:
Impression management explanations of escalation behavior focus on a decision maker's need to justify her past choices to others. The outcome of an investment is rarely free from external scrutiny, and a decision maker may escalate commitment to her original investment to avoid admitting to others that the venture was a failure or that her decision was flawed. Such admissions might cause others to doubt her competence. Furthermore, people tend to punish decision makers for inconsistency... When a decision maker switches from her originally endorsed course of action, observers may take it as a sign of weakness or lack of confidence. Thus...she may choose to escalate commitment to avoid appearing inconsistent.
To be clear, Kelly and Milkman are focused on situations where "objective evidence indicates that continuing with an investment is unwise, and yet an individual chooses to invest further in spite of this," while I'm deliberately expanding the frame to consider how these same dynamics might be leveraged to help us create "virtuous circles" and achieve our goals more readily.
One obvious way I might take advantage of impression management: Write about my goals on a website with my name on it :-)
For an overview of my self-coaching framework, see A Self-Coaching Guide for Leaders at All Levels.
For all my posts on this topic, see my Self-Coaching category.
Note: Many other resources are available based on Edwin Locke and Gary Latham's research, most notably their 1990 book, A Theory of Goal-Setting and Task Performance (which I haven't read) and their 2002 paper, Building a Practically Useful Theory of Goal-Setting and Task Motivation.
Photo by John Trainor. Yay Flickr and Creative Commons.