Meditating on all that God gives to us
Look up Psalm 100, The Jubilate, which we often say or sing at Morning Prayer. This short psalm reminds us to make a joyful noise, and to sing to God. My childhood memories of my mother was of her singing all day, usually hymns or choruses. If you are alone why don't you do that (even if its "Give me joy in my heart" or "All things bright and beautiful"), and if you live with others then find a piece of joyful Christian music on your computer and play it loudly!