If you can't say something nice don't say anything at all.
~Thumper's mother to Thumper, in the Disney movie, Bambi
Think of that the next time you encounter a person in a moment of "quiet" or someone you want to label as shy.
Silence isn't negative, however. Sometimes it just means one is listening. Or tuning inward rather than out. Slogging through daily grind that requires no commentary. Trying to maintain perspective rather than spew forth words that might change your course... or your attitude.
How does one look at a life on a daily basis and single out one gratitude in a sea of many? How does one select a positive without acknowledging that there are negatives at hand, as well?
You choose it. You say something nice. And sometimes you don't say anything at all.