When you are tempted to be discontent or downhearted, look around you.
There is always, always, always, something to be thankful for.
There were many times that I could have been downcast recently... I think that a tool of the enemy is discontentment. He wants you to look around and want what someone else has or to be sad that yours is not as great or as nice. He wants you to covet what is not yours.
I know everyone probably has many things that we would like to improve or change or that we might want... but just look around at your life and see the good there or how you can improve the situation just by changing your heart and being thankful. You will not fill a void with more things. Things will not make you happy. They are only temporary.
Choose to be thankful. Choose to be grateful. Choose to be happy with what God has given you, and do your best to make your situation better with what you have. Happiness doesn't come from stuff or things. It comes from the Lord. It comes from a heart of gratitude and gratefulness.
Choose to have a thankful heart.