Personal goals - keep them to yourself?

I read a shocking article in Newsweek via mental_floss today.

Announcing life goals publicly may have an adverse psychological effect on whether you actually achieve your goal.

According to the scientific study, it is good to have goals... but even better if you keep your goals to yourself. Keep that in mind when you start on you New Year's Resolution list.

So are we doing students a psychological disservice by encouraging them to make public announcements of their academic goals? (e.g., when students say, "I am going to graduate!" and then begin to slack off.)

More importantly, how do we create a psychologically effective sense of urgency and determination to accomplish their goal?

Or does a psychological study of adult behavior not apply to at-risk teenagers?