71 Following in the footsteps of the great apostles of all ages, he knew that the best and most effective way for him to contribute to the salvation of those who would be entrusted to his care was through the cross. It was for them that he put up with all sorts of calumnies, prejudices and opposition, without complaint; for them that he willingly endured the sharp discomforts and annoyances of mind and body that were forced upon him by his daily administration of the Sacrament of Penance for thirty years with almost no interruption; for them that this athlete of Christ fought off the powers of hell; for them, last of all, that he brought his body into subjection through voluntary mortification.
Source: Sacerdotii Nostri Primordia (Vatican.va)