On the day of atonement some translations read to humble ourselves and some translations read afflict your souls. Traditionally people would fast for the day, but some are not able to do that for various reasons so what should you do? The word used means to be made to bow down and is also translated as afflicted, to be dealt with harshly and to be oppressed. While many follow the traditional fasting, others will deny themselves in various ways. What you choose to do in order to confirm your repentance is between you and your Creator.