One time a 1st grader (college now) wrote a thank you card. "Thank you for keeping your promises."
I don't remember what promise I kept, but maybe it has something to do with having a party or something. But I try very hard to keep my promises, and sometimes I say "I promise - wait... I promise, that I don't forget... I will do it.. I will write it down!"
Anyway, after a long day, I'm proud to remember that I kept a promise to send someone some opening notes (I don't think I had a deadline, but it feels so good to deliver on the promise early). It is the perfect finish to a good day.