Matt.5:4 "Blessed are those who mourn for they shall be comforted." Seems like a contradiction, to be joyous if we mourn. However, true joy will only be evident in us if we have the same attitude toward our sin as Jesus does. Sin always brings death. This isn't a perpetual mourning but one that we become sensitive to Gods Spirit when He reveals sin in or around our lives. Mourning in the sense as when a loved one passing. If you mourn this way over your sin, Gods promise is you shall be comforted. Freed from the chains and the death sentence sin had on you. Thus, you are filled with joy. Jesus-others-yourself. Praise God He will never leave us in mourning.