The secret to contentment is not actually a secret. If earning more money and acquiring more stuff is important to you, then you are not going to be a contented person because there will always be more stuff in the world than you are able to acquire, and it is very likely that there will always be plenty of people earning more money than you. Contentment can only come if you choose to have different sorts of goals in your life. In the sixth chapter of his first letter to Timothy, Paul writes:
Godliness does indeed enrich your life with contentment. We brought nothing into the world, and we certainly cannot carry anything out. But we can be content with the food and clothing that we have. People who are determined to be rich fall into temptations and traps and many foolish and harmful desires which cause people to sink into ruin and destruction. The love of money is at the root of all kinds of evil. Some people have wandered away from the faith in their greed, and have caused themselves all kinds of problems.
If you really believe that you are created in the image of God, why will you be wasting your efforts trying to buy fancy clothes and stuff to improve your image? If you believe that your purpose in life is to be part of God’s plan for the world, you do not need to be driven by the desire for accumulation. Your self-worth comes from knowing that God loves you, not from striving to win the approval of others.