At the end of the list of forbidden relations, G‑d authorized the Jewish courts to impose on the Jewish people any additional restrictions they deem necessary in order to safeguard the observance of these laws.
The Need for Precaution
וּשְׁמַרְתֶּם אֶת מִשְׁמַרְתִּי וגו': (ויקרא יח:ל)
[G‑d told Moses,] “You must safeguard My charge.” Leviticus 18:30

This injunction also includes the directive that each of us take our own, added precautions when we see that these are necessary in order to avoid transgressing any of the Torah’s prohibitions.

The fact that the Torah encourages such “safeguards” teaches us that we should never underestimate their importance. Since we are all naturally prone to overestimating our ability to resist evil, it is necessary for us to periodically evaluate our spiritual health – preferably by consulting regularly with a qualified spiritual counselor – in order to determine when additional stringencies are necessary.1