On July 1, 1962, Pope John XXIII issued an encyclical entitled Paenitentiam Agere. It's a beautiful document explaining how the success of the then-upcoming Second Vatican Council would be contingent on the internal and external penances of the clergy and laity.
Thus, John XXIII exhorted all Catholics to redouble their efforts to offer prayerful penances for God's providential guidance at the Council.
I have no idea how well this encyclical was received, but it is interesting that Blessed John XXIII intently sought the prayers and sacrifices of the Church in preparation for this Ecumenical Council. Perhaps our thoughts about what Vatican II should or shouldn't have been should begin with John XXIII's observation that a broken and contrite spirit is essential for determining God's will.
Are we living a penitential life for the sake of the Church, our families, and our final perseverence in grace? It's something to think about as we enter into the Advent season.
Blessed John XXIII, pray for us.