I don’t know who said it, but I picked it up on a slide show a while ago:

“We seldom think of what we have, but often think on what we miss.”

~Author unknown

In response, I’m reminded of a favorite from Science and Health:

“Are we really grateful for the good already received? Then we shall avail ourselves of the blessings we have, and thus be fitted to receive more.”

~Mary Baker Eddy