The mitzvah is made up of three parts:
The will of the One who commands it, the system or technique of the action, and the person who performs the mitzvah.
None of these by itself is enough.
Only by someone performing it is a mitzvah genuine and holy.
Phylacteries lying on a shelf are no more than little boxes and straps, the tzitzit, are no more than a few threads.
A Torah Scroll is holy only when the right person reads from it in the right way.
In short, only when the circle of Divine Will is closed and the circuit of holiness is complete is there a mitzvah.
Thus, the person who performs a mitzvah is in two dimensions of reality, that of normal existence, in which the mitzvah is a fixed act at a very specific point in space and time, and that in eternity, where time altogether ceases to have any meaning.
There is the story of the rabbi who was jokingly asked by a well-to-do member of the congregation:
"Tell me, Rabbi, is it not true that in the prayer of the Shema it is written that for someone who transgresses,the rain will not fall and his work will not prosper?
Well, look at me; all my life I did not pay attention to the laws of the Torah; I don't keep the mitzvot now, and yet, I have wealth and honor. How do you explain it?"
And the Rabbi answered: "From what you have said, I gather that you were once accustomed to reciting the Shema prayer.
And you should know that there is nothing great enough to reward you for this single mitzvah of reciting the Shema.
As for your transgressions, that is something else."
Thus, every mitzvah is a genuine moment of contact with the Eternal, and there can be nothing in life to balance it.
–Rabbi Adin Steinsaltz
From The Long Shorter Way, p. 166, by Rabbi Adin Steinsaltz