The parshah tells us about Yom Kippur, the holiest day of the year. On this holy day we don't drink, eat, wash, or wear leather shoes. It's not very hard to feel holy on this special day when so many things are different. But the name of the parshah is Acharei, which means "afterwards." A Jew must make his life holy not only on Yom Kippur, but also afterwards, during every other day of the year.
How would you describe a holy person?
Some people think a holy person lives far away from the city. There, in peace and quiet, he can concentrate on making himself a better person. He might dress differently from most people, or fast, or eat a very simple diet. He might not take part in what goes on outside of his house, and would spend his time thinking and praying.
But this is not how the Torah teaches us to be holy. Quite the opposite! The Torah tells us to be holy, and connects that commandment with mitzvos that concern food, clothing, marriage, business, farming and more. When we prepare food the way HaShem instructs us, we become holy. When we sew our clothes the way HaShem commands us to - we become holy. When we conduct our business and farm the way HaShem wants us to - we become holy.
We do not have to remove ourselves from everyday life or live far away from people to be holy. We should be involved with everyday things, but in the way that HaShem wants.
HaShem tells us to "be holy, for I am holy." He put His holiness into everything which exists - into clothes, food, and business. If we do these things in the Torah way, then we reveal the holiness which HaShem has placed in them. That is what makes us holy.
(Adapted from Likkutei Sichos, Vol. I, Parshas Kedoshim)