Answer: “Zivug” is unification by way of a screen. If you are resisting your ego, the will to receive pleasure (desire), in order to merge with the Creator for the sake of bestowal, and if you have the force of resistance, a screen, you enter a “Zivug.” It is regarded as “Zivug de Hakaa” (mating while striking).
You push the Upper Light away from your desire to receive pleasure by way of a strike, meaning that you are unwilling to receive it directly, for self-gratification. You are willing to receive this “treat” only to equalize yourself with the Upper Light, and not because you are “hungry,” even though you are really starving.
You are prepared to refuse all of these pleasures and not receive them in order to satisfy your hunger, but to perform a calculation and accept them only inasmuch as you can delight the Host. This is regarded as a strike.
By doing so, you don’t reject the Host but the pleasures that are trying to enter your will to receive directly. You are willing to receive them but indirectly, only if and after you have analyzed whether this will truly be in order to be similar to the Host and connect with Him in mutual bestowal.
From the 2nd part of the Daily Kabbalah Lesson 12/2/10, Talmud Eser Sefirot