To Prepare You For Eternal Good
Jesus says: "Reflect frequently with gratitude and compassion on what I, your Lord and Creator, suffered in My long agony and prayer, when the vehemence of My desires and My love caused Me to bedew the ground with a sweat of blood (before Crucifixion); offer Me all your actions and all that concerns you, in union with the entire submission with which I said these words: 'My Father, Thy will be done;' and so receive all that happens to you, whether painful or agreeable, with the same love with which I send it to you for your salvation. Be grateful in prosperity, uniting yourself with the love which made Me send it to you, condescending to your weakness, so that temporal prosperity may lead you to think of spiritual joys, and to hope for them; receive adversity also in union with the charity with which My paternal love sends it to you, to prepare you for eternal good."
(He gives us grace to handle whatever adversity comes in life.)
The source of all goodness and wisdom is God, and this particular revelation is conveyed through: The Life and Revelations of Saint Gertrude, Virgin and Abbess of..., revelations of God to her, By Sister M. Fra Clare, p.374 (Recommend Bible as primary source and these teachings as secondary)