A sunny spring day, 73 degrees, a slight breeze, my body not aching, and a Diet Dr. Pepper. That is a state in which I find it easy to be content. But contentment in that state is not something I have to learn. It just seems to come naturally. Being happy and satisfied on other days and during other circumstances does not come naturally; contentment has to be learned.
In Philippians 4:11, the apostle Paul says that he has learned to be content in whatever circumstance he finds himself. That includes the good days, the easy days. Of course, when life is easy and things are going well, there is always something to complain or murmur about. But life has hard days, whether it is because of living in a fallen world, experiencing the consequences of our own sin or another person's sin, or spiritual attack.
It is in those hard days that we have opportunities to learn contentment in God. But often we find ourselves murmuring or complaining about the difficulties we experience rather than being content in what God has done, who God is, and what God is going to do.
What God has done
You are in Christ, all of your sin has been forgiven, you have been born again, you have been given the Holy Spirit, and you have been seated with Christ.
Who God is
God is providential and in control of all circumstances and has ordained everything to bring about your joy in him and his glory among the nations. Nothing happens to you that God did not foreordain. Because he is wise, can we be satisfied in an all-knowing Heavenly Father.
What God is going to do
We will be raised again from the dead, we will live forever with God, we will enjoy God's presence without sin.
On the difficult days and during the difficult times, we have a choice: either be content in God (by reflecting on the truth we know), or murmur against God. There is no other choice, and there is no neutral choice.
Showing contentment in God is a testimony to his goodness and grace. Murmuring is of the world.
I'll leave you with this one last thought from Jeremiah Burroughs, 17th century Puritan pastor:
"I labor to do what pleases God, and I labor that what God does shall please me. In active obedience, we worship God by doing what pleases God. In passive obedience, we worship God by being pleased with what God does."
A free, abridged version of the book "The Rare Jewel of Christian Contentment" is available here.