Everything is God's. Nothing is ours.

In Matthew chapter 19, a young man claims to have obeyed all of God's commandments. Jesus tells this seemingly-righteous person (ESV),

If you would be perfect, go, sell what you possess and give to the poor, and you will have treasure in heaven; and come, follow me.

In response, the person goes away depressed, because he had many possessions.

Jesus is demonstrating to the young man that, although he has obeyed the letter of the law, his mind is in the wrong place. He views his earthly possessions as his, or even perhaps as rewards for his ability to keep the commandments. But as Psalm 24:1 (ESV) tells us,

The earth is the Lord's and the fullness thereof, the world and those who dwell therein.

Do we view our homes, bank accounts, careers, families, cars, and even our bodies as our own? We shouldn't--they are blessings from God! Keep Psalm 24:1 on your mind as you pray. Memorize it. Recite it over and over. And do so without ceasing!