When we meet together with the brethren … and celebrate the divine sacrifices with God’s priest, we ought to be mindful of modesty and discipline– not to throw abroad our prayers indiscriminately, with unsubdued voices, nor to cast to God a petition that ought to be commended to God by modesty; for God is the hearer, not of the voice, but of the heart. Nor need He be clamorously reminded, since He sees men’s thoughts. … The Holy Spirit, moreover, suggests these same things by Jeremiah, and teaches, saying, “But in the heart ought God to be adored by thee” (Bar 6:6). And let not the worshipper, beloved brethren, be ignorant in what manner the publican prayed with the Pharisee in the temple. Not with eyes lifted up to heaven, nor with hands proudly raised; but beating his breast, and testifying to the sins shut up within, he implored the help of divine mercy. ~Saint Cyprian
The Fathers know best.