Several from Henry Van Dyke:
Use the talents you possess, for the woods would be a very silent place if no birds sang except for the best.
Gratitude is the inward feeling of kindness received. Thankfulness is the natural impulse to express that feeling. Thanksgiving is the following of that impulse.
Happiness is inward, and not outward; and so, it does not depend on what we have, but on what we are.
. . . and from others:
You are not here to merely make a living. You are here to enable the world to live more amply, with greater vision, and with a finer spirit of hope that leads to achievement. You are here to enrich the world.
~ Woodrow Wilson
Those who wait on the Lord shall renew their strength; they shall mount up with wings like eagles, they shall run and not be weary, they shall walk and not faint.
~ Isaiah 40:31
. . . do it all for the glory of God.
~ 1 Corinthians 10:31b