How can you be grateful for things when you feel sad or depressed, not valued, not important, not enough?
That is a good question.
Today, I am finding myself in this predicament.
What is getting me through this type of situation is the knowledge that Heavenly Father loves me and that His Son, Jesus Christ, has suffered and died for me (and each and every one of us). For these facts, I am extremely grateful. I know that They value me; They consider me important; They think I am enough just as I am.
If you believe in a Supreme Being, even though you might call Him/Her by a different name, rely on your Supreme Being.
If you believe in Nature, watch a sunrise, a sunset, the stars in the firmament, or the rain as it falls. Find the beauty around you and express your gratitude for such creations.
No matter how bleak life might seem in this point in time, it will pass. This situation is not permanent. It is just a glitch that will soon disappear. If nothing above works, just be grateful that time will pass and will take this moment away.
If you find yourself that these sad moments are more frequent that your good moments, please seek help. It is not a shameful thing to turn to specialists (and their prescribed medicine) that can help us through this rough patch of life. You are not alone and you are not meant to go through this alone. Ask for help.