A great question to ask other people: "What are you grateful for?"
Most people are grateful for many things, but this isn't necessarily on the forefront of their minds. It's like the thoughts of being grateful are on the hard disk of their mental computer, but not on the screen of their minds. By asking someone, "What are you grateful for?" they bring the thought of gratitude up to their mental screen.
After some people, when they have answered this question, you might add a comment like, "You are fortunate for that." "That's a wonderful thing to be grateful for." "So you always have what to be grateful for."
(From Rabbi Zelig Pliskin's book: Thank You! Gratitude: Formulas, Stories, and Insights: Artscroll Publishers)