Physical purification is achieved by standing, as much as possible, for purity: pure food and pure sexual relationships or no relationships at all - the purest or none!
In sexual relations the auras of the two people mix together like two bottles of colored water. Let us say that one is yellow and the other is green with lots of germs -- not only physical germs but also the germs in the emotional, mental, and etheric contents of the aura. When the auras mix together, you become a "soup". What did you do to yourself? Your aura is polluted, so your inspiration will stop and you will not have the aspiration to be something. You will stop meditating. You will not read or study. Something falls apart within your system. This is the result of lack of purity. You will not even be able to appreciate beautiful things because your aura is like a soup. Pure relationships and pure food are important.