Some specific penitential practices include the use of hard wooden stools in the refectory, perpetual abstinence from meat (with the exception of poultry at two meals a week) 

narrow wooden planks for beds, and nocturnal vigils before the Blessed Sacrament. 

"By reason of their religious consecration and the apostolic vocation of the Order, the nuns are urged more than the rest of the faithful to deny themselves, take up their cross, and bear the death of Jesus in body and soul, that they may merit the glory of the resurrection for themselves and for others. In imitation of St. Dominic "who while he lived in the flesh walked in the spirit, not merely refusing to satisfy the desires of the flesh, but extinguishing them," the nuns should exercise the virtue of penance especially by faithfully fulfilling everything that pertains to their life."

From the Constitutions of the Nuns of the Order of Preachers

Penitential Practices