Every human being has a need for being valued. This need also extends to people who are successful and surprisingly even to those who are enlightened!
This means we can all touch people by offering sincere praise and appreciation. By so doing you make a positive difference to others and at the same time, you feel good about doing so.
A general positive feedback is better than negative feedback, however, a sincere specific feedback is far more valuable. Take every opportunity to offer sincere specific feedback!