Sometimes it depends on who is doing the praying. The prayers of a virtuous man achieve much.
Case in point:
“Father Seelos, cure me,” was the plea of a crippled man who picked up his crutches and tossed them out a rectory window in Pittsburgh. “My good man,” replied Father Seelos, “I’m no doctor. I cannot cure you.” Nevertheless, Seelos returned a few moments later with a Bible in hand to read from the Gospel of Saint John and to pray intently over his visitor. Then the man slowly stood upright, praising God so exuberantly that he left the crutches behind.