Our infinite sadness can only be cured by an infinite love.
The cross of Christ, embraced with love, never brings sadness with it, but joy, the joy of being saved and of doing a little of what he did on the day of his death.
Jesus on the cross feels the whole weight of the evil, and with the force of God's love he conquers it; he defeats it with his resurrection. This is the good that Jesus does for us on the throne of the cross. Christ's cross, embraced with love, never leads to sadness, but to joy, to the joy of having been saved and of doing a little of what he did on the day of his death.
If sadness comes to you one day with an invitation, tell it you are committed to joy and will be faithful to it your whole life long.