Pastor Charles website FOR ME TO LIVE IS CHRIST has a good article about Eternal joy in Jesus Christ here.
While we enjoy things down on this earth, they will all soon fade away. But we are glad that we can in this earthly life have some enjoyment in them today.
But there is this eternal inheritance that we who are believers can have, which has been given to us by our Heavenly Father. Who by His mercy and grace has given us this wonderful inheritance which is salvation.