Let your gratitude to others last for a long time. A classic American joke tells of a congressman who, when he solicits a constituent's vote, learns that the man is planning to vote for his opponent. "But how can you do that?" the congressman objects. "Don't you remember that time ten years ago when your business burned down, and I arranged for you to get a low-interest loan from the Small Business Administration? And what about the time when your daughter got in trouble with the police overseas, and I arranged for her to be released and sent back to the United States? And the time when your wife was sick, and I helped get her admitted to the special hospital she needed?" The voter answers, "That's all true, but what have you done for me lately?"
"What have you done for me lately?" is the ingrate's question. Judaism's perspective is very different. When King David is on his deathbed, and offers his final words of wisdom and advice to his son and successor, Solomon, he reminds him to "show kindness to the sons of Barzillai of Gilead, and let them be of those that eat at your table, for they befriended me [many years ago] when I fled from Absalom your brother" (I Kings 2:7) . . .
Remember those who have helped you at different moments in your life:
• family members, teachers, and rabbis who inspired you and believed in you
• friends with whom you are perhaps no longer in touch, who showed you loyalty and warmth
• an employer who gave you a break, perhaps when you were young and inexperienced
Even if these people are no longer in a position to help you, indeed specifically because they no longer are in a position to help, you should find a way to make known to them how you feel. After all, a person who expresses gratitude only to those who can help him is manipulative, not grateful.— Joseph Telushkin in A Code of Jewish Ethics: Volume 1