All 613 are in a sense compressed into each individual mitzvah.
The oneness of the mitzvot should not be viewed as the mechanical construction of diverse elements for the sake of a common higher purpose, but rather as a unity similar to that of nature itself.
Each part of creation draws nourishment from all the other parts, and thus enfolds into itself something of their essence.
The all-encompassing character of each mitzvah is a multifaceted idea, treated on a number of levels of interpretation, from the mystical and esoteric to the halakhic and pragmatic.
Just as the deliberate violation of a single mitzvah is to be regarded, in a sense, as an act of rebellion against Divine authority in general, so too can the acceptance and fulfillment of a single mitzvah be seen as an acceptance of the fundamental, primary meaning of the mitzvot in general, an acceptance of the yoke of the Kingdom of Heaven.
The fulfillment of one mitzvah is thus tantamount to the recognition of the basic principle of the Divine-human connection and all that it signifies.
However isolated, it is an act fraught with significance.
This view is in accord with that of halakhah itself: the failure to fulfill a given mitzvah, for whatever reason, does not exempt one from the fulfillment of other mitzvot.
For example, one who actively violates Shabbat is not thereby relieved of the duty of lighting Shabbat candles.
From Teshuvah by Rabbi Adin Steinsaltz