There is a different kind of prayer without ceasing; it is longing. Whatever you may be doing, if you long for the day of everlasting rest do not cease praying. If you do not wish to cease praying, then do not cease your longing. Your persistent longing is your persistent voice. But when love grows cold, the heart grows silent. Burning love is the outcry of the heart! If you are filled with longing all the time, you will keep crying out, and if your love perseveres, your cry will be heard without fail.
Source: Augustine’s Expositions of the Psalms