A few favorites:
"A thankful heart is not only the greatest virtue, but the parent of all the other virtues."
(Cicero)“You don’t have to be afraid of praising God too much; unlike humans He never gets a big head.”
[Paul Dibble]
"You say, 'If I had a little more, I should be very satisfied.' You make a mistake. If you are not content with what you have, you would not be satisfied if it were doubled."
[Charles Haddon Spurgeon]
"Nothing purchased can come close to the renewed sense of gratitude for having family
and friends." [Courtland Milloy]