Matthew 5:4 “How blessed are those who mourn! for they will be comforted.”
While we can tend to mourn pain in our lives, true morning is a deep conviction of sin.
Understanding the severity of sin and the state of man causes a son to mourn.
We had to be poor in spirit before we could be filled with the Holy Spirit and here again is another example of exactly the same thing.
Conviction must of necessity precede conversion.
A real sense of sin must come before you can experience the true joy of salvation.
This is the whole essence of the Gospel.
"So many people spend all their lives trying to find this joy of a son. They say they would give the whole world if they could only find it, or could be like some other person who has it. Well, just that in ninety-nine cases out of a hundred this is the explanation. They have failed to see that they must be convicted of sin before they can ever experience joy. Some people do not like the doctrine of sin. They dislike it intensely and they object to its being preached. They want joy apart from the conviction of sin. But that is impossible; it can never be obtained. Those who are going to be converted and whom wish to be truly happy and blessed are those who first of all mourn. Conviction is an essential preliminary to true conversion."
This is a dead serious summary of chapter 5 in Studies in the Sermon on the Mount by D. Martyn Lloyd-Jones.