Instead, God asks us to give Him our best. To go "all out." If everything we have belongs to God in the first place, then contentment should come by realizing that God is simply loaning us our resources, our talents, our families, etc, for this particular moment in time. God deserves all that we have. He deserves one hundred percent of our effort. If we give Him that, we can be assured of a peaceful heart regardless of the outcome.
As Paul tells us in Philippians 4:11-13 (NIV):
I am not saying this because I am in need, for I have learned to be content whatever the circumstances. I know what it is to be in need, and I know what it is to have plenty. I have learned the secret of being content in any and every situation, whether well fed or hungry, whether living in plenty or in want. I can do everything through him who gives me strength.We can be happy whether we have the most or the least. The goal is to give God our best and then let Him decide the outcome. When our desire to please God outweighs our desire to please ourselves, that's when we'll find true contentment.