As you may already know, that's from William Arthur Ward.
Anyway, here's from another encourager:
"You have it easily in your
power to increase the sum total of this world's happiness now. How? By giving a
few words of sincere appreciation to someone who is lonely or discouraged.
Perhaps you will forget tomorrow the kind words you say today, but the
recipient may cherish them over a lifetime." —Dale Carnegie
And more encouragers please, indeed.