Rabbi Shlomo Freifeld OBM constantly reminded his students to always give each other an encouraging word. There needn't be anything specific in mind; just to wish someone success in any - and all - of his endeavors can have such a powerful effect. As he put it, "it opens up wellsprings!"
Rav Freifeld would marvel at those students who would come to his yeshiva after experiencing one defeat after another, having their spirits crushed by unyielding faculty in other institutions. After a few weeks of firm but gentle encouragement from the fellow students and staff in Shor Yoshuv, they would begin to believe in themselves and start accomplishing beyond their wildest imaginations.
It's important to note that many times there isn't any malicious intent behind the discouragement, either. Often those people think that they are doing the person a favor by "grounding him in reality" and protecting him from his own "too-lofty" aspirations. What they are really doing is shaping the other person's world-view to expect failure and mediocrity.
While we all have to be aware of our capabilities - and limitations - we can still hope for the best and let others know that we believe in them, and want to see them succeed. By doing so, we open up the wellsprings of accomplishment that allow people to realize their potential.
I would suggest that we should all take it upon ourselves to encourage our friends, family and peers. It doesn't have to be overbearing or unnatural; just a sincere wish to see them thrive and do well. The chances are high that we'll make someone's day.
Inspired by Reb Kalonymos Kalman's ideal of a group of people coming together with the common goal of enhancing their service of God, increasing their sensitivity to all things spiritual, strengthening their love of acheinu kol beis Yisrael, and unlocking the enormous potential that we all have to cleave to the Almighty.
Interaction and discussion of practical ideas and concepts toward this end, culled from any Torah true source is welcome and appreciated.
Observations and personal experiences are also welcome; the point is to grow!