One day one of my friends asked her friend one simple question, on a scale of 1 to 10, how would you like to rate your level of joy? She replied that I am very happy in my life, living a relaxed life, doing all those things that I want but I am not joyful.
So here the difference will come out between happiness and joy. Joy is different from happiness as the source of joy is totally different from happiness. Happiness is totally depends on what happens where as joy is independent of them all. So where can we find the joy? God!
Yes the real source of joy in someone life is God. God is the source of energy and god is the source of joy. God will remain same as on yesterday, forever and today. We can rejoice on his actions during good days and bad days.
Now why joy is only in God because praying God is the most important thing in life. Joy is something that you can find within you. Happiness is totally based on outcomes of other. When you have set goals in your life and when you start achieving them you will feel happy about that and that happiness is a state of mind for sometime whereas joy is something that keep you calm in every kind of situation. The main source of joy is in praying to god. The joy will come automatically when you will start talking to yourself.
When you start devoting yourself in the services of God and when you will start spending more and more time in services of God, you will start talking to yourself and you will feel joy in worship God. This joy will give you real happiness in your life.
So treat God as your real source of joy and when you find joy in him, you will automatically be joyful in your life.