What to do about the mitzvot encumbent upon us but which circumstances beyond our control prevent us from performing?
Take for example the offering of korbanot in the Beit HaMikdash...
...the Chachamim say that anyone who engages himself in the laws of the Chatat (sin) offering, it is as if he offered a Chatat; and anyone who engrosses himself in the laws of the Asham (guilt) offering, it is as if he offered an Asham. Likewise, when one engages himself in the laws of any of the korbanot, it is as if he brought those offerings (Menachot 110a).
The idea behind this is that every deed performed in the world possesses an inner soul. The soul of a mitzvah is the words of Torah that discuss that mitzvah. These ideas especially pertain to the korbanot, for the essence of the korbanot is to express our connection to Hashem. Therefore, when one cannot actually bring the offerings, the study of them is considered a substitute for their sacrifice (see also Maharal, Gevurot Hashem, chapter 8). (Source)This is why we have a section on korbanot in our daily prayers. Every time you say it aloud with real intent and yearning for the opportunity to bring your offerings to the Holy Temple in reality, it counts as having performed the mitzvah itself.
And this concept can be applied to any mitzvah which for the time being remains out of our reach.