Advisory notice: Do not attempt to take up such a practice without the counsel and permission of your spiritual director, and for minors this is expressly forbidden unless you have the consent of both your parents and that of your Father Confessor. This practice can be very injurious to one's physical health, and it can lead to great spiritual delusions and a ruinous pride if it is undertaken under the impulse of self-love and is unaccompanied by other exercises of exterior and, above all, interior mortification. I mean, if you can take the discipline unto the shedding of blood and yet answer rebukes with sharp and bitter words or satiate the palate with all sorts of deliciousness, then there is a serious spiritual malady there.