Rambam - Sefer HaMitzvos: Negative Mitzvot 352, 347, 346: Negative Mitzvot 352, 347, 346

Negative Mitzvah 352: Prohibition against an uncle-nephew relationship
Leviticus 18:14 "Do not act immodestly with your father's brother"

It is forbidden to act immodestly with your father's brother (your uncle).

Negative Mitzvah 347: Prohibition against marriage with a married woman Exodus 20:13 "You shall not commit adultery"
A person is not allowed to act immodestly with another man's wife.

Negative Mitzvah 346: It is forbidden to come into physical contact with a "Niddah"
Leviticus 18:19 "Do not come close to a woman who is a Niddah"

"Niddah" is a specific personal condition which can only apply to a woman. A man is not allowed to have physical contact with a woman who is considered "Niddah."

The natural tendency is to treat matters of the spirit as luxury items -- sort of an appendage to life. Eating, sleeping, making money -- these things are given priority over all and the time dedicated to them is sacrosanct. But prayer, meditation and study fit in only when you feel like it, and are pushed aside on the slightest whim.
You've got to make your priorities faithful to your inner self. You've got to ask yourself if this is what your life is all about. Set a schedule for spiritually enriching activities. Be as tough with that schedule as a workaholic would be with his business.

From: Bringing Heaven Down to Earth by Tzvi Freeman - tzvif@aol.com