Man finds it hard to get what he wants, because he does not want the best; God finds it hard to give, because He would give the best, and man will not take it. ~ George MacDonald
When we are truly free, we will want what is best. We will want what God wants. The best gifts God can give us are intimacy with himself, and to make us like Christ: honest, fair, brave and kind. He wants to make our hearts free and our wills strong.
We can find joy in doing that which is actually good for us. God loves us and wants us to know what is best.
The best possible thing for each of us is to find joy in loving others; the best possible thing for each of us to do is to do what Jesus asks of us. If we understand that trusting and obeying Jesus leads to intimacy with God, and with others, and that is what we desire above all else, then we will find great joy in doing God's will. Jesus valued intimacy with his Father above all else. He knew he could only enjoy intimacy with his Father while he trusted and obeyed him.* God's will is life.
Am I saying that I always do God’s will? No. I have a long way to go before God finishes making me. I don't always find as much joy in doing God’s will as Jesus did. I need God’s Spirit (whom he gives to those who set their heart on obeying him. See Acts 5:32.) Sometimes life can be very stressful. And if I’m not careful people will get the better of me. When I get angry or frustrated and desire to harm instead of help, I have to tell God I’m sorry and ask for his help. In other words, I’m learning to value my relationship with God above all else. I am slowly becoming like Christ. And because of this, I am no longer enslaved to many of the things that once enslaved me. God wants us to know the joy of doing what seems impossible. (And without God's help doing his will is impossible.) He wants us to overcome the world, instead of being overcome by it. The more a man is what a man was meant to be, the freer that man will be.
Like anything worth having, gaining freedom from sin will require real struggle. Sometimes it will be physically and emotionally demanding. It is not natural to the weak willed to go the extra mile. It is not natural for a slave to sin to admit to being wrong and to ask God for help. But to all those who set their hearts on being intimate with God and so set about obeying Jesus, God will set free.
*When Jesus was crucified, he did not enjoy what was being done to him; but he did find joy in doing his Father's will. It is for the same reason that Paul could rejoice while in prison. God's will is liberty. See The Hope of the Gospel by George MacDonald. If you don’t know what God wants from you read the book of Luke. And then do the thing that is placed right in front of you.