108 There never was a time, Venerable Brethren, when the salvation of souls did not impose on all the duty of associating their sufferings with the torments of our Divine Redeemer. But today that duty is more clear than ever, when a gigantic conflict has set almost the whole world on fire and leaves in its wake so much death, so much misery, so much hardship; in the same way today, in a special manner, it is the duty of all to fly from vice, the attraction of the world, the unrestrained pleasures of the body, and also from worldly frivolity and vanity which contribute nothing to the Christian training of the soul nor to the gaining of Heaven. Rather let those weighty words of Our immortal predecessor Leo the Great be deeply engraven upon our minds, that by Baptism we are made flesh of the Crucified: and that beautiful prayer of St. Ambrose: "Carry me, Christ, on the Cross, which is salvation to the wanderers, sole rest for the wearied, wherein alone is life for those who die."
Source: Mystici Corporis Christi (Vatican.va)