17 It remains, Venerable Brethren, in order to guard and preserve the fruit of the Spiritual Exercises which we have been praising and to revive its salutary memory that we should earnestly recommend a pious custom which may be called a brief repetition of the Exercises namely a monthly or trimestrial recollection. This custom which, to borrow the words of Our Predecessor of holy memory, Pius X, "We gladly see introduced in many places" and flourishing especially in religious communities and among pious priests of the secular clergy we earnestly desire to see adopted by the laity also. For it would prove a real benefit more especially for those who are prevented by the cares of their family from using the Spiritual Exercises. For these recollections might supply in some measure the advantages to be derived from the Spiritual Exercises. In this manner, Venerable Brethren, may these Spiritual Exercises be extended everywhere through all the orders of Christian society and if they are diligently performed a spiritual regeneration will follow. Piety will be enkindled, the forces of religious will be nourished, the apostolic office will unfold its fruit bearing branches, and peace will reign in society and in the hearts of all.
Source: Mens Nostra (Vatican.va)