We’re only three weeks into the New Year, but plenty of New Year’s resolutions have already evaporated. What is it about human nature that makes it difficult to truly effect change?

Scores of successful people have achieved their goals by changing their focus. So what are the secrets to developing a new approach?

One of the most well-known examples of keeping a New Year’s resolution relates to maintaining a healthy lifestyle by exercising, losing weight and eating better. According to the Wall Street Journal, data from gym attendance at fitness centers throughout the country indicates that resolve to stick to exercise resolutions begins to waiver in the third week of January. A 50% surge from December, when people start their new exercise regimen, takes a nosedive by the end of March.

The same article reports that according to research performed at University College London, forming a habit requires about 66 days and setting a specific goal is more effective than having vague goals. Essentially, a new habit (or goal) should be realistic enough to be attainable, but challenging enough to be worthwhile.

How many times have we set goals that sound impressive, but given the resources at hand—time, budget and workloads—it simply isn’t attainable. On the other hand, some organizations set goals every year that they can very easily attain, especially if they involve bonus or incentive compensation.

In terms of tactics, psychologists say stating the “how and when” of a goal is also helpful in achieving it. For example, a producer might say, “Every morning at 9 a.m. for 90 minutes, I will make prospect phone calls. Then I’ll get a cup of coffee as a reward.”

Clearly, getting into a routine and developing good habits is critical to long-term success. In the above example, a producer might make it clear to everyone at the agency that beginning at the appointed hour, they require no interruptions with the exception of emergencies. He or she might even place a sign outside the office that says, “Please do not interrupt me until 10:30 a.m. I will respond to your need after that time.”

We all make plans, but then life gets in the way. It’s too easy for well-intentioned chatter to distract us from our goals. This closed-door sign approach signals to your colleagues that you are serious about your goals—and makes them reconsider the status of their own.

Speaking of exercise, the February issue of the International Journal of Cancer provides some promising statistics indicating exercise creates a hormone known as Irisin, which can significantly reduce the number of aggressive breast-cancer cells in laboratory cultures. The research indicates that women who exercise have a 30-40% reduced risk of breast cancer and an improved chance of survival.

Dave Evans is a certified financial planner and an IA contributor.